Hi,
Please do try these troubleshooting steps that may help in solving the issue.
- Start with a hard reboot, remove the battery and unplug the AC adapter then press and hold the power button for 20 seconds then see if it would boot up normally.
- If these doesn't work do try to run it in Safe Mode.
- While the laptop is booting up, repeatedly press on F8 until it loads Advanced Boot Options then select Safe Mode.
- Once in Safe Mode do run System Restore, restore it back to an earlier date or time before the problem even happened.
- Here's how to run System Restore:
http://windows.microsoft.com/en-ph/windows7/restore-system-files-and-settings
- If all these will not work you'll need to reinstall Windows 7.