Here is a partial solution it would seem:
1. Run Malwarebytes Pro
2. reinstall Windows
3. find correct drivers because model number was wiped in the bios
4. open MS-Word docs with Wordpad
5. first line of open file in Wordpad has gibberish but text can be read afterwards
Again, it seems to me this is not encryption issue because the same garbage-gibberish appears across different ppt and word files when they are opened. I suspect only headers have been corrupted in data files.
Any luck with pdf files anyone?