Have you tried what richc46 suggested?
If your boot image is corrupt, the system should boot to a Win 7 install DVD. If you really can, select language then on the next page select Repair on the lower left. Then see what messages you get. If if asks to repair, click OK. If it will let you, select the install you want to repair the next, then startup repair. When it is done, try rebooting, if it doesn't work, try the repair again.
The Startup repair works in stages so it may take 3 attemps to repair your system.