我在使用 Ubuntu 时遇到了问题。它总是以低图形设置启动，并且运行缓慢。
我安装了 Lubuntu 桌面环境，然后我意识到我不喜欢它，所以我尝试删除它。我可能将 SeatDefaults 设置为空白或：
user-session=ubuntu greeter-session=unity-greeter我如何将其恢复为 Ubuntu？我不记得我所做的所有更改，也不确定如何修复它们。我不想丢失我的应用程序或文档。
编辑：运行Nathan Smith建议的代码后我得到了这些输出
sudo apt-get purge --auto-remove abiword abiword-commonabiword-plugin-grammar abiword-plugin-mathview ace-of-penguins audacious audacious-plugins audacious-plugins-data blueman chromium-browser chromium-browser-l10n chromium-codecs-ffmpeg elementary-icon-theme esound-common galculator gdebi gdebi-core gecko-mediaplayer giblib1 gnome-icon-theme-full gnome-mplayer gnome-system-tools gnome-time-admin gnumeric gnumeric-common gnumeric-doc gpicview gtk2-engines-pixbuf guvcview hardinfo indicator-status-provider-pidgin leafpad libaacs0 libabiword-2.9 libaudclient2 libaudcore1 libaudiofile1 libbinio1ldbl libbluray1 libbs2b0 libcddb2 libcompfaceg1 libcue1 libencode-locale-perl libept1.4.12 libesd0 libexo-1-0 libexo-common libexo-helpers libfile-listing-perl libfluidsynth1 libfm-data libfm-gtk-data libfm-gtk1 libfm1 libfont-afm-perl libgdome2-0 libgdome2-cpp-smart0c2a libglade2-0 libgmlib0 libgmtk0 libgmtk0-data libgoffice-0.8-8 libgoffice-0.8-8-common libgringotts2 libgsf-1-114 libgsf-1-common libgtkmathview0c2a libguess1 libhtml-form-perl libhtml-format-perl libhtml-parser-perl libhtml-tagset-perl libhtml-tree-perl libhttp-cookies-perl libhttp-daemon-perl libhttp-date-perl libhttp-message-perl libhttp-negotiate-perl libid3tag0 libimlib2 libio-socket-inet6-perl libio-socket-ssl-perl libjpeg-progs libjpeg-turbo-progs liblink-grammar4 libloudmouth1-0 liblwp-mediatypes-perl liblwp-protocol-https-perl libmailtools-perl libmcrypt4 libmenu-cache1 libmowgli2 libmpg123-0 libnet-dbus-perl libnet-http-perl libnet-ssleay-perl libobrender27 libobt0 libonig2 liboobs-1-5 libopts25 libots0 libpisock9 libresid-builder0c2a libsidplay2 libsocket6-perl libtar0 libtidy-0.99-0 libtie-ixhash-perl libtimedate-perl libuniconf4.6 liburi-perl libvdpau1 libwebcam0 libwv-1.2-4 libwvstreams4.6-base libwvstreams4.6-extras libwww-perl libwww-robotrules-perl libxfce4ui-1-0 libxfce4util-bin libxfce4util-common libxfce4util4 libxfconf-0-2 libxml-parser-perl libxml-twig-perl libxml-xpath-perl libxss1 lightdm-gtk-greeter link-grammar-dictionaries-en lm-sensors lubuntu-artwork lubuntu-artwork-12-04 lubuntu-core lubuntu-default-settings lubuntu-desktop lubuntu-icon-theme lubuntu-software-center lxappearance lxappearance-obconf lxinput lxkeymap lxlauncher lxmenu-data lxpanel lxpanel-indicator-applet-plugin lxrandr lxsession lxsession-edit lxshortcut lxtask lxterminal mplayer2 mtpaint ntp obconf openbox openbox-themes osmo pcmanfm pidgin pidgin-data pidgin-libnotify pidgin-microblog plymouth-theme-lubuntu-logo plymouth-theme-lubuntu-text python-pysqlite2 python-xklavier scrot sylpheed sylpheed-doc sylpheed-i18n sylpheed-plugins synaptic system-tools-backends transmission ttf-lyx uvcdynctrl uvcdynctrl-data wvdial xfburn xfce-keyboard-shortcuts xfce4-power-manager xfce4-power-manager-data xfconf xfonts-100dpi xpad xscreensaver xscreensaver-dat
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package 'indicator-status-provider-pidgin' is not installed, so not removed
Package 'libfm1' is not installed, so not removed
Package 'libmenu-cache1' is not installed, so not removed
Package 'libxfce4util4' is not installed, so not removed
E: Unable to locate package abiword-commonabiword-plugin-grammar
E: Unable to locate package libabiword-2.9
E: Couldn't find any package by regex 'libabiword-2.9'
E: Unable to locate package libfm-gtk1
E: Unable to locate package libgmlib0
E: Unable to locate package libgmtk0
E: Unable to locate package libgmtk0-data
E: Unable to locate package libobrender27
E: Unable to locate package libobt0
E: Unable to locate package openbox-themes
编辑_2/更新：
运行Nathan Smith建议的代码后：
sudo apt-get purge --auto-remove abiword abiword-plugin-mathview ace-of-penguins audacious audacious-plugins audacious-plugins-data blueman chromium-browser chromium-browser-l10n chromium-codecs-ffmpeg elementary-icon-theme esound-common galculator gdebi gdebi-core gecko-mediaplayer giblib1 gnome-icon-theme-full gnome-mplayer gnome-system-tools gnome-time-admin gnumeric gnumeric-common gnumeric-doc gpicview gtk2-engines-pixbuf guvcview hardinfo leafpad libaacs0 libaudclient2 libaudcore1 libaudiofile1 libbinio1ldbl libbluray1 libbs2b0 libcddb2 libcompfaceg1 libcue1 libencode-locale-perl libept1.4.12 libesd0 libexo-1-0 libexo-common libexo-helpers libfile-listing-perl libfluidsynth1 libfm-data libfm-gtk-data libfont-afm-perl libgdome2-0 libgdome2-cpp-smart0c2a libglade2-0 libgoffice-0.8-8 libgoffice-0.8-8-common libgringotts2 libgsf-1-114 libgsf-1-common libgtkmathview0c2a libguess1 libhtml-form-perl libhtml-format-perl libhtml-parser-perl libhtml-tagset-perl libhtml-tree-perl libhttp-cookies-perl libhttp-daemon-perl libhttp-date-perl libhttp-message-perl libhttp-negotiate-perl libid3tag0 libimlib2 libio-socket-inet6-perl libio-socket-ssl-perl libjpeg-progs libjpeg-turbo-progs liblink-grammar4 libloudmouth1-0 liblwp-mediatypes-perl liblwp-protocol-https-perl libmailtools-perl libmcrypt4 libmowgli2 libmpg123-0 libnet-dbus-perl libnet-http-perl libnet-ssleay-perl libonig2 liboobs-1-5 libopts25 libots0 libpisock9 libresid-builder0c2a libsidplay2 libsocket6-perl libtar0 libtidy-0.99-0 libtie-ixhash-perl libtimedate-perl libuniconf4.6 liburi-perl libvdpau1 libwebcam0 libwv-1.2-4 libwvstreams4.6-base libwvstreams4.6-extras libwww-perl libwww-robotrules-perl libxfce4ui-1-0 libxfce4util-bin libxfce4util-common libxfconf-0-2 libxml-parser-perl libxml-twig-perl libxml-xpath-perl libxss1 lightdm-gtk-greeter link-grammar-dictionaries-en lm-sensors lubuntu-artwork lubuntu-artwork-12-04 lubuntu-core lubuntu-default-settings lubuntu-desktop lubuntu-icon-theme lubuntu-software-center lxappearance lxappearance-obconf lxinput lxkeymap lxlauncher lxmenu-data lxpanel lxpanel-indicator-applet-plugin lxrandr lxsession lxsession-edit lxshortcut lxtask lxterminal mplayer2 mtpaint ntp obconf openbox osmo pcmanfm pidgin pidgin-data pidgin-libnotify pidgin-microblog plymouth-theme-lubuntu-logo plymouth-theme-lubuntu-text python-pysqlite2 python-xklavier scrot sylpheed sylpheed-doc sylpheed-i18n sylpheed-plugins synaptic system-tools-backends transmission ttf-lyx uvcdynctrl uvcdynctrl-data wvdial xfburn xfce-keyboard-shortcuts xfce4-power-manager xfce4-power-manager-data xfconf xfonts-100dpi xpad xscreensaver xscreensaver-data
它处理起来没有任何问题，但是当我重新启动时，我被卡在 Ubuntu 的启动屏幕上。
我的下一个问题是，我是否可以将整个系统恢复为默认设置，同时丢失所有内容，但我将从头开始，而不需要 USB、CD、DVD 或其他可启动媒体来启动系统？
先感谢您。
答案1
我认为你可以按照问题答案中概述的步骤进行操作如何删除除 Unity 之外的所有桌面环境，跳过他们正在删除的除 lubuntu-desktop 之外的其他桌面环境。（他们还安装了 xubuntu、cinnamon 和 gnome）
编辑：现在就试试吧。我快速编写了一个 Python 脚本来删除原始命令中错误中出现的软件包。它给了我：
sudo apt-get purge --auto-remove abiword abiword-plugin-mathview ace-of-penguins audacious audacious-plugins audacious-plugins-data blueman chromium-browser chromium-browser-l10n chromium-codecs-ffmpeg elementary-icon-theme esound-common galculator gdebi gdebi-core gecko-mediaplayer giblib1 gnome-icon-theme-full gnome-mplayer gnome-system-tools gnome-time-admin gnumeric gnumeric-common gnumeric-doc gpicview gtk2-engines-pixbuf guvcview hardinfo leafpad libaacs0 libaudclient2 libaudcore1 libaudiofile1 libbinio1ldbl libbluray1 libbs2b0 libcddb2 libcompfaceg1 libcue1 libencode-locale-perl libept1.4.12 libesd0 libexo-1-0 libexo-common libexo-helpers libfile-listing-perl libfluidsynth1 libfm-data libfm-gtk-data libfont-afm-perl libgdome2-0 libgdome2-cpp-smart0c2a libglade2-0 libgoffice-0.8-8 libgoffice-0.8-8-common libgringotts2 libgsf-1-114 libgsf-1-common libgtkmathview0c2a libguess1 libhtml-form-perl libhtml-format-perl libhtml-parser-perl libhtml-tagset-perl libhtml-tree-perl libhttp-cookies-perl libhttp-daemon-perl libhttp-date-perl libhttp-message-perl libhttp-negotiate-perl libid3tag0 libimlib2 libio-socket-inet6-perl libio-socket-ssl-perl libjpeg-progs libjpeg-turbo-progs liblink-grammar4 libloudmouth1-0 liblwp-mediatypes-perl liblwp-protocol-https-perl libmailtools-perl libmcrypt4 libmowgli2 libmpg123-0 libnet-dbus-perl libnet-http-perl libnet-ssleay-perl libonig2 liboobs-1-5 libopts25 libots0 libpisock9 libresid-builder0c2a libsidplay2 libsocket6-perl libtar0 libtidy-0.99-0 libtie-ixhash-perl libtimedate-perl libuniconf4.6 liburi-perl libvdpau1 libwebcam0 libwv-1.2-4 libwvstreams4.6-base libwvstreams4.6-extras libwww-perl libwww-robotrules-perl libxfce4ui-1-0 libxfce4util-bin libxfce4util-common libxfconf-0-2 libxml-parser-perl libxml-twig-perl libxml-xpath-perl libxss1 lightdm-gtk-greeter link-grammar-dictionaries-en lm-sensors lubuntu-artwork lubuntu-artwork-12-04 lubuntu-core lubuntu-default-settings lubuntu-desktop lubuntu-icon-theme lubuntu-software-center lxappearance lxappearance-obconf lxinput lxkeymap lxlauncher lxmenu-data lxpanel lxpanel-indicator-applet-plugin lxrandr lxsession lxsession-edit lxshortcut lxtask lxterminal mplayer2 mtpaint ntp obconf openbox osmo pcmanfm pidgin pidgin-data pidgin-libnotify pidgin-microblog plymouth-theme-lubuntu-logo plymouth-theme-lubuntu-text python-pysqlite2 python-xklavier scrot sylpheed sylpheed-doc sylpheed-i18n sylpheed-plugins synaptic system-tools-backends transmission ttf-lyx uvcdynctrl uvcdynctrl-data wvdial xfburn xfce-keyboard-shortcuts xfce4-power-manager xfce4-power-manager-data xfconf xfonts-100dpi xpad xscreensaver xscreensaver-data
如果这不起作用，你只需使用
sudo apt-get purge --auto-remove lubuntu-desktop
正如那里提到的，执行该命令后，您还应该自动清理以丢弃不需要的旧包数据，并使用智能依赖处理进行更新和 dist-upgrade，如下所示：
sudo apt-get autoclean
sudo apt-get update
sudo apt-get dist-upgrade
更新 #2：尝试重新启动计算机，然后按 Ctrl+Alt+F1 而不是正常登录。这应该会让您进入文本模式 tty1 shell（Ctrl+Alt+F7 将让您返回 GUI - 一旦 GUI 修复！）。输入您的用户名和密码进行登录。
如果你很幸运，你会有互联网（要找到答案，请输入“ping askubuntu.com”等待几秒钟，如果你收到除错误/超时之外的响应，则它有效并且你可以使用 ctrl+c 停止它）否则你可以进行搜索并找到如何从命令行连接到网络的指南。
现在你可以尝试以下方法
sudo apt-get --fix-broken install unity unity-greeter
然后重启。另外，检查一下 LightDM 的显示管理器文档& Ubuntu 专用文档在这里。您可能需要重新安装/重新配置它才能正常工作
如果这不起作用，或者这似乎比获取可启动媒体更难，那么最好的选择可能是尝试 Xubuntu 或您认为效果最好的其他 Ubuntu 版本。从实时会话中，您应该能够移动重要文件，然后进行安装。有时也可以创建省钱的安装（例如主磁盘上的实时会话），而无需可启动媒体，但它们可能很棘手，因为您必须使用大量命令行实用程序和/或运行虚拟机。
祝你好运！