Turn on the computer.
When the initial blue HP screen appears, press the F10 key repeatedly until a recovery menu appears. The progress indicator that first appears does not indicate that a recovery is taking place. The progress indicator represents the time before the recovery process is started.
To perform a destructive recovery, click Advanced, and then click Yes.
You will then have to wait for anything between 30 minutes and an hour, (maybe longer)
The machine will reboot a few times in this process, DO NOT touch anything just let it keep going until you get the Windows Setup screens, they will prompt for you to enter you language, keyboard language, computer name, password ect..ect...
Enter the information when prompted to and let the machine reboot when prompted to, after so long you will be taken to the desktop.
Once there follow these steps:
1) When the restore has finished you will need to do all the Windows Updates, keep going back and checking as there are updates for updates of updates, depending on the age of your system this could take some time but its very important that you do this to fully patch the system, just keep going back until you get "Windows is up to Date", to do this, go to Start > All Programs > Windows Update > Check for Updates > Install UPdates.
2) If your system came with a preinstalled Anti-Virus program then that is likely going to be out of date and will need uninstalling via "Programs and Features" in control panel.
3) Install ONE AntiVirus program, as you are using Windows 7, Windows Defender will take care of your Anti-Spyware for now and the Firewall will suffice for the time being, you can find some very good free Security programs HERE
3) Again, depending on the age of the system, alot of your other programs non microsoft programs are going to be out of date and will need updating, this is especially true of Adobe Reader and Flash Player
if you have them preinstalled.
4) Your machine will have all the junk that comes bundled with new machines on it so you will need to uninstall the programs that you removed last time if you removed any, If you are not sure on what to remove or did not remove any when you got the system then you can just ignore this item.
If you have any worries or concerns before you begin the Restore please post back and I will give you as much information as you need.
Once you have finished the Restore, please post back if you need any advice on the above steps I have outlined for you.
If you can complete the above steps with out problem then please post back and I will provide you with some advice on how to minimize the chances of this happening in the future and how to keep your system fully patched and secure.
If you have any questions at all then just ask away.