我尝试阅读较早的帖子，但它们似乎都不相关。出于某种原因，当我尝试在 TeXworks 中编译任何文档时，我收到错误：
This is pdfTeX, Version 3.1415926-2.5-1.40.14 (MiKTeX 2.9 64-bit) entering extended mode (C:/Users/USER/Documents/ads.tex LaTeX2e <2011/06/27> Babel <v3.8m> and hyphenation patterns for english, afrikaans, ancientgreek, ar abic, armenian, assamese, basque, bengali, bokmal, bulgarian, catalan, coptic, croatian, czech, danish, dutch, esperanto, estonian, farsi, finnish, french, ga lician, german, german-x-2013-05-26, greek, gujarati, hindi, hungarian, iceland ic, indonesian, interlingua, irish, italian, kannada, kurmanji, latin, latvian, lithuanian, malayalam, marathi, mongolian, mongolianlmc, monogreek, ngerman, n german-x-2013-05-26, nynorsk, oriya, panjabi, pinyin, polish, portuguese, roman ian, russian, sanskrit, serbian, slovak, slovenian, spanish, swedish, swissgerm an, tamil, telugu, turkish, turkmen, ukenglish, ukrainian, uppersorbian, usengl ishmax, welsh, loaded. ! LaTeX Error: File `article.cls' not found. Type X to quit or <RETURN> to proceed, or enter new name. (Default extension: cls) Enter file name:
我编译了之前可以正常工作的文件，然后出现此错误。我以前也遇到过这个问题，尽管我什么都没做，但问题已经解决了。现在又出现了。我不明白为什么。有人能帮帮我吗？我尝试编译的产生上述错误的文件是：
\documentclass[a4paper]{article}
\begin{document}
oko
\end{document}