The recovery disk is a boot disk. You put it in the drive (usually the first one), reboot your computer, and the recovery disk will load and reinstall everything on your system.
Recovery disks are used to set all your software back to the state it was in when it was originally configured in the factory. None of your files will be saved.
If you wish to back up your files, there are many ways to do this. If you have a CD or DVD burner, burn your files off onto disks. You could put all your files onto flash drives or an external/secondary harddrive. If the files that you wish to save aren't too large, you can email them to yourself, run the system recovery, and download them from your email.
I'm very curious though. What problem are you having with your system that causes HP to tell you to reinstall everything? There are many times when tech support will tell you this simply because they do not have an answer for you or it would take too much time to explain how to fix the problem.
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