What have you done to it recently? How about this: hold option while booting, and select the Macintosh HD. Your Mac is certainly not dead, the worst case scenario is that your drive is dead, which is doubtful. How about booting your MacBook up with the disks, and seeing if the drive is there under Disk Utility, run a test, make sure everything is okay.
Another thing... turn it on and let it sit, while it shows that question mark, it is looking for an OS. If it doesn't find one in about 5 minutes, try the other suggestions. If the drive is okay and it can't find the drive, reinstall the OS.
Wait, do you have another Mac? FireWire Target Disk Mode the MacBook and get your data off there to another Mac.