standard ps/2 keyboard on my sony vaio laptop VGN AR 750E/B not working

I'm not sure what you mean by "standard ps/2 keyboard".

If you mean the built-in keyboard, it probably doesn't need any drivers. If it's not working you can get a replacement on eBay, etc. If you are not up to replacing it yourself, take it to a shop.

I looked at the specs and did not see a ps/2 port on the machine but if you have a ps/2 keyboard that you want to connect to it, you can get a ps2 to usb adapter and use one of the usb ports. That won't require drivers.

If you just want to use a standard sized keyboard, you can get a standard usb keyboard and plug it into any usb port. It won't require drivers either.