Hi,
- Are you facing this issue while working with Microsoft office products or with all programs?
- What is the make and model of the keyboard?
- Have you tried turning off “Num Lock” button to the right hand side of the keyboard?
I would suggest you to check the issue with Onscreen keyboard and see if it is working.
Refer:
http://windows.microsoft.com/en-us/windows7/Type-without-using-the-keyboard-On-Screen-Keyboard
Method 1:
Step 1: Safe modeBoot your computer in safe mode and check for the issue.
To start your computer in Safe mode
http://windows.microsoft.com/en-US/windows7/Start-your-computer-in-safe-mode
Step 2: Clean boot
If you do not face the issue in safe mode, then put your computer in clean boot and check for the issue.
How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7
http://support.microsoft.com/kb/929135
Note: Once you are done with clean boot, please follow step 7 in the article to put your computer back to normal startup.
Method 2:
Run a virus scan on your computer.
www.microsoft.com/security/scanner
Note: If any infections are detected during the scan, there might be a chance of data loss as the infected files will be deleted.
Hope this helps.