In this scenario we have two possible ways of working, first a problem with the keyboard hardware which implies a replacement and second a software problem that is solved by executing some program or driver.
First, let’s rule out that it’s a keyboard hardware problem. Then I attach a page to perform a write test, If the keys work as expected, the problem is not the keyboard hardware.
If the tests were satisfactory, it is not a hardware problem, so please perform the following steps one by one to eradicate the problem.
1. Till your problem is resolved and you need to do urgent and limited typing, use Onscreen Keyboard – Type OSK in Windows Start Search Box (Cortana) > Click On-Screen Keyboard
2. Run Keyboard Troubleshooter
Type Troubleshoot in Windows Start Search box > Click Troubleshoot > Scroll down and click Keyboard > Run the troubleshooter > Follow onscreen directions
3. Uninstall & reinstall Keyboard Driver
Windows Key+X (Or right click on Start) > Click Device Manager > Expand Keyboards > Right click on Standard PS/2 Keyboard > Uninstall > Reboot the computer to reinstall
4: Turn off filter keys in Ease of Access
Type ease in Windows Start Search box > Click Ease of Access > Click Make the Keyboard easier to use > Ensure Turn on filter Keys is not checked