Spacebar on my pc wont snap back on after removal

If you look at the buttons that the space bar fits on to they are probably made of plastic and are in the shape of two letter "H"s joined at the centre.

Normal wear and tear causes one leg to snap off and it si impossible to fix them with glues

You can buy individual key bases off the net with and instruction of how to fit them

www.laptopkeys.co.uk

Looks like something has been spilt down behind the spacebar or much dirt has accumulated in among the keys, or the spring has come unstuck the rebounds the spacebar back to it's original position. You will have to open the back of the notebook and try to assess what's wrong back there. I would asume that your spring has come loose from the spacebar and all that needs to be done is to clip it back into it's position, eithir that or a good clean to get rid of all the sticky matter that is back there.