Restore Windows 7 to Its Normal State

1. Use Safe Mode. Safe Mode is the best place to start to fix your computer when it is malfunctioning. This mode can be used to combat certain types of viruses, as well as a diagnosis tool if you are unsure of why the computer is not functioning. If the computer boots and functions in Safe Mode, then you know that the problem is with a program, driver or other file, rather than with the computer itself.
2. Reboot in Safe Mode. Reboot in Safe Mode from the Shutdown menu, if accessible.
3. Hit F8. If the Shutdown menu is inaccessible, you can restart the computer and repeatedly press F8 while it is loading. This should give you access to the Boot Menu.
4. Select Safe Mode and hit enter. Press the down key to access the Safe Mode option and hit enter.
5. Begin fixing your computer. Once the program starts, you can begin attempting to fix your computer. There are a number of different methods you can try and which you use will largely depend on what kind of problem you are having.
6. Delete files associated with a known virus in your system that the virus would normally make inaccessible.
7. Download or run anti-virus software that a virus would normally make inaccessible. This may require you to boot in Safe Mode with Networking.
8. Uninstall recently installed programs which you suspect may be causing problems.
9. Update drivers if you suspect that severely outdated drivers may be the problem.
10. Do a System Restore, which is similar to the Last Known Good Configuration below. Do this by searching System Restore from the start menu and following the prompts.Don’t forget to scan for affected programs.