First try booting into
Safe Mode with Networking to install, update and run a full scan with
Malwarebytes. Then once cleaned run
SFC -SCANNOW Command and work through these
troubleshooting steps.
If Safe Mode is not working, download, burn to CD or write to flash stick, boot and run a full scan with
Microsoft Standalone System Sweeper.
Once the System is clean if it won't start boot into
System Recovery Options via the F8 menu or disk as shown in tutorial, run
Startup Repair repeatedly no matter what it reports. Post back results.
If this fails, try System Restore from Recovery Options list, then if that fails open a Command Line to run
SFC -SCANNOW Run in Command Prompt at Boot.
As a last resort boot free
Partition Wizard bootable CD to Explore C to see if your files are intact,
make sure C or the 100mb System Reserved partition (preferred) is marked Active, then click on HD to highlight it, from Disk tab select Rebuild MBR, Apply. If Windows 7 doesn't start and you restored Active flag, run
Startup Repair 3 Separate Times.
If these all fail you can copy out your data using your Windows 7 DVD or Repair CD:
Copy & Paste - in Windows Recovery Console or Paragon Rescue CD.
System Repair Disc - Create
Then run Factory Recovery from its partition or disks you made or order from Tech Support, or find a Windows 7 installation DVD to clean reinstall using Product Key on COA sticker:
Clean Reinstalling Windows 7