There is a protected dip switch under the keyboard. It should have an anti static amber clear sticker on it. Did you possibly switch this?
I did, on an attempt to have the Dpad appear as an arrow key to the OS. I thought I flipped switch 2; being from left to right. I should have looked harder. I flipped switch 1.
In doing so, the keybord and mouse became unresponsive. Luckily nothing was damaged in doing so, and I could return to normal by correcting the switches.
Also, have a look at this thread:
This is the dip switch in question. It seems some people have encountered physical problems with it.