My PS3 isn't reading any discs for some reason.

It all happened during a game of LittleBigPlanet when, as the pod was loading after completing one of the levels, the screen went white. I pressed the reset button but after about 5 minutes it still hadn't reset, so I switched it off from the back. When I turned it back on again it didn't load the disc at all. I tried taking it out, putting it back in; taking it out, resetting then putting it in once the PS3 is loaded up; putting in a different disc, but none of these worked. When I put a disc in it comes up with the loading thing in the top right corner of the screen and does nothing else. Any help on this issue at all?