Hp Pavilion dv5-1008ca windows formated

Hello,

i have a machine of HP pavilion dv5-1008ca, Windows was doing some problem and in the meantime unfortunatly my brother formatted the c:\ drive, means he deleted the windows and replaced it with the cheap local windows, Now i want to recover its original windows i am trying but i don't know exactly how to do, Also i checked the d:\hp recovery partition it is showing the used space of 8.5gb but there are no filesof recovery, that partition is showing empty inside. i don't have a windows recovery CD.
Please someone help me and guide me that how can i recover its original windows.

Thanks in advance