Try to search sites like download dot com for your specific file. If you can dl the file to a floppy try that. If you dont have a floppy drive get an external one. Another site you can search for files is filehippo dot com. Anyways you "might" have to reinstall. Here's hoping you run backups on a regular basis.
BTW, microsoft does have pretty strong tech support once you get past the first tier of tech support. Call em up. Another way though not as archair as floppy is a flash/jump/thumb drive. Best of luck I hope any of this helped.