Keyboard not working , No drivers in device manager

my pc is having trouble detecting the keyboard , tried sys restore ,changed keyboards but still no detection,the keyboard light flashes when i turn on the pc ,also there's no keyboard hw in device manager list ,using a ps2 keyboard ,help!,
there's a single beep when i turn on the pc

somehow I was happy that I did managed to solve the problem on my own by unplugging the keyboard and shutting down the PC and then turned it back ON,switched off the PC went for my lectures ,came back and the keyboard was still working fine until it stopped working and whenever I pressed any of the keys the CPU started beeping on every key I pressed ,its quite annoying to say the least ,had to unplug from the PS/2 port ,shutdown the computer then plug it back and then start the computer and just hope that somehow it will work ,which it did after 3-4 attempts and thus right now I am able to type such a long post without the onscreen keyboard ,Hope any one can chip in and help me solve this annoying problem
PS:When the keyboard doesnt works there are no keyboard drivers in the device manager list ,now its there
Got to do something with the Drivers and stuff ,did a system restore 2-3 times but still having the same problem

Try a new keyboard... you can get one cheaply enough to make that an easy troubleshooting step. I'd suggest a USB keyboard as it's possible there's something wrong with your PS/2 port.