My laptop keyboard got jammed. I am sure there is a key or set of keys to press to release the jam because I can recall I had a problem with my old laptop some 2 years ago which was sorted thus. The present problem is with the new dell laptop three weeks old. Can somebody help.

Awesome tune, that's Macy Gray, called I Cry.

Sounds like you have a stuck key.
There are a couple of ways to clear this.
The first to try is a simple case of running your finger along ALL the keys and ensureing that they all move.
Another thing to try is blowing all the rubbish out of your keyboard with some canned air, easily available form most computer shops.

Can you define what you mean by a jam more completely. Generally when something is jammed, its physically stuck. Nothing software can do with that. In that case Ben's answer is helpful.

If, however, its stuck where what you press produces a different result (like all caps), that may be fixable with a key combination. So a fuller explanation will help us help you.