Can't log in -- how can I rollback driver?

[Manikle]

My son installed a mouse driver on his computer which instantly caused the keyboard to become unresponsive.
Tried rebooting into safe mode--which it does--but can't log in because the keyboard won't respond at the login screen onward.
How can I remove the offending (or roll back to the previous) driver and restore keyboard function?
TIA

 

[Marnomancer]

Any specifications on the keyboard? Was it a firmware upgrade, or some software tool?

 

[Manikle]

Sorry, should have added more details.
He was replacing the mouse and installing drivers for it from a disc.
He mentioned that "it said something about a conflict" but apparently he went ahead and installed the driver anyway.
I tried another keyboard, to see if that would work--it didn't. Neither keyboard is USB.
The mouse is USB.

Would "Use last known good configuration" be a good thing to try?
I don't want to further complicate matters

 

[Manikle]

Believing that people who post questions on the internet should be courteous enough to post solutions or workarounds, when found, here it is:
I bought a USB keyboard and it works. Problem is apparently either the serial port itself or the serial keyboard driver--probably the latter.

 

[c3h899]

Additionally, you should have attempted to the on-screen keyboard (accessibility menu) and typed with your mouse, from there browse to device manager (right-click the My Computer icon) find the offending hardware and either disable it to attempt support for other hardware or manually "update" the drivers being sure to specify MS Generic ones or known good drivers.

 

[Manikle]

Isn't the accessibility menu only found in Windows?
I was unable to log in to Windows.
(My son had rebooted, thinking that the keyboard might then become responsive.)
It's good info to know, though, should a future problem arise.

 

[c3h899]

In Win7 click on the funny-looking icon, in XP and previous perhaps not.