OMG this is a tuff issue. You shold start with resetting the SMU.
MacBook, MacBook Pro
If the computer is on, turn it off.
Disconnect the AC Adapter and remove the computer's battery.
Press and hold down the power button for 5 seconds and then release the button.
Reconnect the battery and AC Adapter.
Press the Power button to restart the computer.
BOOT TO STARTUP MANAGER
try booting to the install disk from startup manager.
if you cannot boot to startup manager after resetting smu and pram that you are KO'ed
if you can boot to startup manger and you see a bootable volume try your hard drive first and you may want to safeboot, during an apple safeboot the OS runs a repair disk and can take a while. if you get to the desktop remove and login items or startup items and reboot. but I would backup all dats if you get the darn thing to boot!
If you can boot only te disks try and archive and install.
If nothing seems to work, if you are still under your 1 year warranty apple may have a free repair for you...