Sony Vaio Laptop Keyboard not working

[M.Mouse]

This one has me stumped.

Sony Vaio VGN-FZ21E running 32bit W7. I installed a legitimate copy of W7 Home Premium on it for the owner a year or so ago. All running fine until two days ago when he booted and found the keyboard was not working when he tried to enter his password.

Using the on-screen keyboard to enter the password the laptop boots but once booted the laptop keyboard still does not work.

I booted from a USB floppy drive into DOS and the laptop keyboard functions perfectly in DOS!

Device manager is showing the keyboard correctly as a PS/2 keyboard, driver update reports the driver(s) are up to date.

I used a genuine W7 Home Premium SP1 disk to repair the OS. All worked as it should but still the keyboard doesn't work.

The laptop has Avast on it. I ran Hitman Pro, Combofix, tdsskiller, Spybot S & D and Malwarebytes with one or two suspect items found but the problem remains.

The keyboard doesn't work in safe mode either.

Plugging in a USB keyboard works.

It has me stumped and Google has not thrown up any answers.

I have also tried removing battery and power, etc, etc.

I would be grateful for any suggestions however wacky!

[green granite]

Try un-instaling it in Device manager and then reboot, but remove the usb keyboard when it shuts down and see if if 'finds' the keyboard.

[M.Mouse]

Thanks for that but I have indeed already tried that to no avail.

[Milo Minderbinder]

either
a windows update has installed the wrong driver - you would have been better trying a system restore or driver rollback as repairing windows will not affect a "wrong" driver......
or the keyboard is dead
or you have a fault on the keyboard controller on the motherboard

[M.Mouse]

The first thing I did was roll back using Restore to a couple of days before the event with no change and the driver rollback button is greyed out.

The keyboard works if I boot the computer into DOS.

I suspect you are right that it is a hardware fault.

I am just about to stick another blank HDD in and load a clean copy of the OS and see if the keyboard works then I think it will prove whether it is a hardware or software issue.

[Saab Dastard]

I booted from a USB floppy drive into DOS and the laptop keyboard functions perfectly in DOS!

I suspect you are right that it is a hardware fault.

Does not compute!

Others with this problem have found the underlying cause to be anything from bad battery to failing hard disk to BIOS settings to registry errors.

Here's one fix that might be worth investigating:

Code 10 Device manager/ Keyboard not working, mouse not working /ps2 (http://hateadub.wordpress.com/2011/04/20/code-10-device-manager-keyboard-and-mouse-not-working/)

SD

[M.Mouse]

Thanks Saab, I too came across that likely solution but that didn't work either. Late last night I bit the bullet and did an up to date back up of all the data and reformatted the disc. Clean install and the keyboard works!

The irritation is that as in all the cases of PC glitches if I knew I would have to do a reinstall then I would just get on with it but because most glitches can be fixed with a bit of perseverance, and this one seemed as if it should be quite simple, I instead wasted many hours before doing so!

Thanks for all the contributions, much appreciated.