|one of 3 things seems likely:|
1) you have a key on your motherboard that is stuck. tap the heck out of your Fn key, as well as all your Ctrl, Alt, and Shift keys.
2) your computer (operating system) has switched keyboard modes from standard western world american english setting to some other style. See if you can use your mouse to checkout keyboard settings in the control panel.
3) your keyboard is toast. hit dell/ebay for a replacement keyboard (the cheapest part of a laptop).