OS not found

I shut down my pc yesterday normally by clicking shut down button in start. Today when I try to start my pc it says "Operating system not found". I've un plugged my other Hard-disk and tried to restart several times. But nothing. My os is/was window 10. It was installed in CRUCIAL MX500 3D NAND...

I have a Samsung RF511 with a Nvidia GT 540M. I've been using for a good time already and it always worked perfectly, without getting too heated up. A couple months ago my laptop started showing an strange behaviour: Windows 10 started to freeze, only shutting down with the power button. After...