Like shadow said, try other games.
If other games in better condition don't work, try cleaning the laser with some Isopropyl Alcohol on a qtip (the higher the percentage the better. 70% probably fine and seems to be more common in my area at least, but I tend to prefer 91% whenever I can get it)
If cleaning the laser eye doesn't work, the laser is probably burnt out. Same thing happened to my OG Xbox. Copying games into the hard drive so often caused it to just give up on me.