The only way to fix this large amount of corrupted files in Windows 7 is to do a repair installation/Inplace upgrade.

• Insert your Windows 7 DVD or mounted a Windows 7 ISO
• Run setup.exe from the DVD/mounted ISO
• during setup select upgrade

This repairs Windows but keeps are programs.

The only way to fix this large amount of corrupted files in Windows 7 is to do a repair installation/Inplace upgrade.

• Insert your Windows 7 DVD or mounted a Windows 7 ISO
• Run setup.exe from the DVD/mounted ISO
• during setup select upgrade

This repairs Windows but keeps are programs.

In 2015, Microsoft backported a DISM command from Windows 8 to Windows 7 to repair files. Look if it is possible to install the update KB2966583, open a command prompt as admin and run DISM /Online /Cleanup-Image /Scanhealth to try to repair files. But if this fails, try the inplace upgrade. Still is still the best option for Windows 7 to make sure it gets fully repaired.