Desktop or laptop model?
Did you spill ANY liquid on the keyboard? Rubbing alchool should not cause any problem, but any other liquid definitely can ruin your keyboard.
For a desktop type, replacing the keyboard is very easy and relatively cheap. Does using a replacement keyboard solve your problem?
On a laptop, try connecting an USB keyboard. Does it work?
You may have something that intercept the key strokes and don't properly forward them. It may be an utility/accessory application or a buggy malware.
Install and run some anti-virus. (some very good free offerings are AVG free, Avira free version, Avast free version)
Install and run some anti-spyware. (one of the best is Spybot)
If you use some utility that intercept keystrokes, you may need to reinstall it.
Electro, July 2014
