Using a similar choice of words, I'd say, "It allowed me to not forget the language." But a native speaker would usually say something more like, "It helped me remember the language."

The word "to" needs to be inserted. "It allowed me TO not forget language." This makes it a sentence. Now, there is the meaning of the sentence to consider. The addition of the articles "the" or "a" narrows the subject "language", and will change the meaning of the sentence. Without articles, "It allowed me to not forget language" would mean "It" allows you to be able to remember how to communicate (speak with, listen to, and understand other people) With the article "the", the word "language" is specific to the language other sentences refer to, English, French, or Russian for example. "It allowed me to not forget the language" With the article "a", the word "language" is not specific, and can refer to any language or one of several languages. "It allowed me to not forget a language" Also, note the second L in the word "allowed" I hope this helps

It allowed me to not forget language. (note correction of minor spelling error and addition of "to"). I can't be sure what your intended meaning is but maybe you were trying for: It helped me to not forget the language.-- or -- It helped me to remember the language ("it" being a method or device and "the" added to indicate a specific language instead of language in general)

1) You can compile code or a book, but it's better to formulate (eg) a question. 2) It alowed me not TO forget (the) language. Please note that most likely the sentence exists in the context, and it may require an article.