When troubleshooting a computer keyboard, first check whether the keyboard is plugged in properly, and use a different PS/2 or USB port or connect another device to the same port to ascertain whether the port or the keyboard is at fault. Restart the computer, and check whether the Num Lock and Caps Lock keys are functioning properly while the operating system is booting up. If the keys work, uninstall recently installed programs to verify which one is causing problems.
To check whether the operating system recognizes the keyboard, access the Device Manager dialog box by opening the Control Panel, clicking on the Hardware and Sound link and selecting the Device Manager option. If there is an exclamation mark next to your keyboard, or if it’s listed in the Other Devices section, update the keyboard driver by using the Windows Update function or manually updating it from the Device Properties dialog box. To do this, double-click on your keyboard, open the Driver tab, and click on the Update Driver button. If the keyboard was disabled, click the Enable button.
If you’re using a wireless keyboard, resynchronize it with the receiver, or use a different USB port for the receiver. If this fails, reinsert the batteries, or put in a new set. Finally, check whether devices located between the receiver and your keyboard are causing interference by placing the at least 8 inches away from the devices.