Question My hard drives arent working

[Coolioyes]

So when i plug in only c drive it works but when i put another drive. The computer says no operating system found

 

[CountMike]

So when i plug in only c drive it works but when i put another drive. The computer says no operating system found

Much more details needed.

 

[SkyNetRising]

So when i plug in only c drive it works but when i put another drive. The computer says no operating system found

When you connect additional drives, then boot sequence changes.
You have to go into BIOS (boot priority settings) and set proper boot sequence.