[SOLVED] I accidentally set c drive as active and now windows says no OS found

[Aeroshoom]

So I accidentally did that to my c drive and now windows says no is found. So I need to reinstall windows? PLEASE HELP.

 

[RealBeast]

So I accidentally did that to my c drive and now windows says no is found. So I need to reinstall windows? PLEASE HELP.

If you can boot with a repair disk, you can either do a repair install or use diskpart commands to make the MBR partition the active partition. However, if you cannot do that, you may be able to do an inplace upgrade like THIS.