|First before doing anything, remove the battery and try booting.|
If that works, time to replace the battery.
If that does not work attempt repair via safe mode.
Tap F8 key as you are booting up. You will get an options screen.
Try the "Last Known Good Configuration (your most recent settings that worked)" first.
If that does not work try the "System Restore" option next
This option restores your computer's system files to an earlier point in time without affecting your files
For other options look here:
Also if you need a recovery CD as you do not have access to windows 7 DVD, there is a windows 7 recovery CD specially crafted for use in repairing PCs which will not even boot into safe mode.
For that look at post #1 in the following thread which is about Vista Recovery CD. However the same page also has a Windows 7 Recovery CD.
☺ When everything else fails, read the instructions.