Is it possible to install Windows on your Comp and not lose all the files(rewrite)?

Take it to your local computer shop and they will back up your drive before formatting it.

Otherwise, get a DVD burner or an external hard drive and back all the data up on your own.

I suggest the first option (shop) because setting up windows can be a bit tricky for you.

Why do you want to reinstall Windows?

Depends on the versions, but when you go to install, it asks if you want to format the hard disk first. If not, you can install it over the top of the old one and it just upgrades the operating system files or overwrites them if it is the same version.

But you will have to reinstall your old programs again in some cases...

As someone whose husband tried to follow the "do not format" rule and wiped 5 years of family photos, might I suggest that it will cause you far less grief in the long run to have your OS on it's own hard drive. It doesn't have to be very large, and to keep all your other folders on a second slave hard drive. During the life of your operating system, the chance is high that you will have to reinstall it at some stage and it is far better to have it on a separate HDD to precious family photos and really important assignments.

yes it is possibel.

while installing Windows again, choose the option, upgrade. DO NOT FORMAT THE Hard Disk.

alternatively there is repair option whihc u can choose while installing the Windows.

Yes. During the reinstall, don't format the partition.