If you can boot to DOS, rename the CONFIG.SYS file (this sounds like directory file problems. keyb.com is a keyboard file. )

Run the SCANDISK and see if you can get things back, particularly after reinstalling Windows.

***IF YOU CAN'T GET THINGS TO CHANGE*** take it to a repair shop and say you think your hard drive is dying and you need it fixed. It very well may be hardware (it's beginning to sound like it) and you will want your data backed up and restored.