Is your PC custom built or is it branded???
If it's branded (like dell.msi,lenovo,etc.) i'm sure there's a restore key like when you start it up you need to press a key (ex. F3)
In my case,one of my computers' O.S. got corrupted (Msi WindTop AE1990) and all i did is i pressed "F3" and the pc did all of the restore stuff.
I hope this one helps