Do you have the windows 7 DVD? If so
You may have to set the DVD drive as irst boot device (it is probaly already set so you can move to step 2
boot from the DVD
A Black screen will appear with the words 'Press any key to boot from CD or DVD', Press Any key to start the booting process
The 'Windows is loading files' screen will now appear with a progress bar.
After a few minutes the Microsoft copyright window ill appear and another small progress bar will be visible
You will next see a Blue curtained screen
Next the Language option screen will appear Select your language and keyboard language and the Click the Next button
At the bottom left of the next screen - the Install screen, Click on the Repair Your Computer option
The System recovery options will now search for your Windows installation
Once the Windows installation has been located, Highlight it and then Click the Next button
The set of recovery options now appears, Click on the Option you require and follow the on screen prompts.
I suggest you first try doing the startup repair from the DVD menu.