efiD
Hello;
Allow me to welcome you to the HP forums!
You might be able to do this yourself. Just press F11 while rebooting and when the HP Recovery Manager comes us, choose the option to do a complete factory reset. You will lose everything on the drive because that reformats the drive. When done, you should have all the partitions back.
If that does not work, then you will have to order recovery media from this link and use that: http://support.hp.com/us-en/document/bph07143
Instructions for doing the recovery : http://support.hp.com/us-en/document/c04758961
Good Luck
I am a volunteer and I do not work for, nor represent, HP