In terms of simply restoring it -- you can't!
If you purchase HP Recovery Media and run that, it will totally reset your PC, including recreating the Recovery partition, but it erases the ENTIRE DRIVE in the process -- and high price to pay to get it back.
If you simply want a Recovery solution, then read on ...
My suggestion is you consider using a third-party solution known as Macrium Reflect (MR).
I prefer to use third-party recovery solutions for the following reasons:
1) More flexibility and reliabilty -- can make recovery media as often as you like, not restricted to one attempt, which if it fails, then you are stuck.
2) More media options -- can create media in DVD, USB stick, or external drive format
3) Mounting option -- can "mount" the save images as virtual "drives" and extract individual files and folders
4) WinPE boot option -- can install a special boot option that allows you to boot to recovery information and do a repair or restore from there -- when Windows will not boot
What I recommend is the following:
1) Download and install Macrium Reflect (MR) from here: http://www.macrium.com/reflectfree.aspx
2) Run MR and choose the option: "Create an image of the partition(s) required to backup and restore Windows" to write a full backup to an external drive, USB stick, or DVDs
3) Use the option to create a boot USB stick or CD
My experience is that MR, when using the High Compression option, typically can compress the saved image file to about 50% of the USED space in the OS partition. This means if you have an 80GB OS partition, and 40GB is used, MR only needs about 20GB to store the image file.
I use this all the time and it typically takes less than 15 minutes to do the image backup and about the same time or less to do a restore. Plus, MR has the option to Add a Recovery Boot Menu entry. This allows you then to boot into WinPE, and you can then use that to do a restore -- when you can't boot into Windows!
NOW, you have the means to restore a full working system from the external drive, USB stick or DVDs in only a few minutes.
Good Luck