@ Technical:
No, there are quite 15 languages for avast! But here, in forums, just English...
I think, that "today" meant that replies to his post should be written in easy english
@toady: There is a chance that the files avast deleted were system files that come with Windows installation. If Yoy know their names and (that would be the bast) version You can try to restore them using msconfig.exe utility and "Expand files" (or something like that - I have polish version of Win XP - don't know how this button is named in Your Win; see attached picture). If by any chance deleted files come from any installed later app, see file's Properties tab (I know that may be difficult, because Avast will block acces for that file) - there may be some info about manufacturer and/or application that file come from, reinstall it - this should be the easies way to recover lost files.
P.S. Of course, first try to detect and remove ALL viruses and/or other malicious programs that infected Your computer