You need the HP Recovery DIsks as a backup to the HD Recovery partition failing to run correctly. These disks should have been made when you set up your computer.

Make sure you are running recovery correctly from its partition: HP Recover Windows 7 Operating System Using HP Recovery - HP Customer Care (United States - English)

If it won't run or complete, you'll need to either contact HP tech support to order the disks, or find a Win7 installation DVD for your version to clean reinstall with the Product Key on COA sticker following these steps: Reinstalling Windows 7