The question is kinda stupid, my apologies because as mentioned by Cody Gray, Whatever program you use for taking image of C drive must have a restore option. One such program, which i personally use is "DriveImage XML", available free at http://www.runtime.org/
What you do is you take an image of your C drive or whatever drive you wanna backup (preferably at a time when you believe your system is working absolutely fine). You should create the backup in some external drive. In case your windows later gets corrupted, all you have to do is format C and install a fresh copy of window. Install the above-mentioned or whatever program you used for taking image. select "Restore" and you PC should work as it worked at the time you took the image.
Hope it works for all