I think you'd better contact with your direct vendor and HP first to find solution of recovery of the Windows 7 preinstalled. Besides that, I would make an Windows 7 installation media such as USB drive or burned DVD+/-R disc with which to boot up your computer and make a refresh installation. After Windows 7 successfully installed, pay visit to HP websites where you could search the proper drivers or contact with HP support.
You can download the Windows 7 ISO from the above website, the product key might be placed the back cover of your laptop, or you might need to remove the battery to find it. Anyway, your further feedback is welcome, and I wish you good luck.