i have RADEON 7310 hd graphics but the game(COD4) i want to run is slow on my laptop tell me what can i do to play this game

That card does meet the minimum requrements but on a laptop you likely have a slow CPU, along with the slow video card and a slow hard drive and I'm guessing not a lot of RAM.

Best thing to do is buy a better computer. Even a used $200 laptop will be a lot better than what you have.
 


Your only option is to buy a faster computer. For a laptop, for a low end gaming system new would be about $600. Used you can likely find one for $300, maybe less if you go for an older Core 2 Duo system but with a good video card.