Some keys on my toshiba laptop are locked, how do I unlock them?

Just some? I thought it was normally all or nothing.

The first thing to check is if there is a key on the keyboard that does it. Laptop's tend to have a lot of functions that you activate by holding a function key (FN) and then pressing an appropriate key. Take a look at the keyboard and look for a key with an image that might signify locking the keys on a keyboard and try that.

What keys? Define Locked? You really need to supply more info if you want us to help.

All the keys have stopped working, there is a sound when I press any key. I cannot type anything. It's a toshiba Tecra S2 laptop, it was working until yesterday, I don't know what happened. I had lent it to somebody.

The fn key is there, but I can't see the other one with an image or something.

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.