Maybe filter keys or sticky keys are on?
Try this Solution…
- Click “Start” and select “All Programs.” Click “Accessories” and select “Ease of Access.” in windows XP. Or Click “Start” and search “Ease of Access” in Windows 7,8,10.
- Click “Ease of Access Center.”
- Click “Make Keyboard Easier to Use.”
- Click “Set Up Sticky Keys.” Deselect the checkbox that says “Turn on Sticky Keys When Shift is Pressed Five Times.”
- Make sure the box that says “Turn on Sticky Keys” is not checked. Click “OK” to save your changes.
- Click “Set Up Filter Keys.” Uncheck the box that says “Turn on Filter Keys.” Uncheck the checkbox next to “Turn On Filter Keys When Right Shift Is Pressed For 8 Seconds”. Click “OK” to save your changes.
- Click “OK” again to save all of the keyboard accessibility changes you have made.
Hope this will help to solve your problem.