My macbook does not advance after apple logo neither starts in safe mode. Please help!

Please help me. I am in urgent need. I have lots of data of my experiments. My macbook (2009) does not move ahead after apple logo neither does open in safe mode. My OS is mountain lion 10.8.2. What should I do to repair my macbook myself. I have used repair disk utility. All hard disc gets repaired using disc utility still it has the same problem. Before that my macbook start to slow down heavily and finally one day it got crashed or stuck up in apple logo for ever. Please help me!!!