USB keyboard not working after RegEdit change

[zx2012]

I was trying to fix a CODE 39 error for a CD-DVD driver on our Dell Optiplex PC.

 

I followed the instructions at Your CD drive or DVD drive is missing or is not recognized by Windows or other programs

 

When I rebooted the USB keyboard no longer works in Windows XP SP3 making the PC unusable. I've tried safe mode as well.

 

The keyboard does work in F2 BIOS setup but I have to move all the video cables around to directly connect the monitor rather than going via the splitter to the projector.

 

How can I restore the registery key from another PC?

[pwds]

Can you not just roll back to the previous restore point?