Try a PS2 keyboard, if you get the keyboard working you can do the following:
Just get a copy of the registry keys you changed, from a friend's PC who is running the same OS.
On friend PC, start regedit and go to:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class
Then select File Menu --> Export
Copy the .reg file to a floppy/CD/USB Pen
Backup your registry first, then copy the .reg file you got from your friend's machine onto your machine then double-click and .reg file. After it updates; restart your machine and you should get your mouse and keyboard functionality back.
Hope that helps....
