Question PC Issue Please Help!!

Dec 20, 2019
Hi all,
Wasn't sure whether to put this in Systems or Windows so hope this is ok.

Basically, having just built my first pc, today I took one of the hard drives out of my old PC to reuse in the new one. I had formatted that hard drive so there was nothing on it.

Next, I plugged a very old hard drive that was in my old pc but not plugged in, as I wanted to go through it and see what was on it. This old hard drive did have Windows installed on it, too. My only other hard drive containing my OS and all my files was already plugged in, I never plugged it out.
However, on booting my PC, things did not go so well. Initially, with the 2 hard drives plugged in, it did eventually boot and go to desktop screen, however I then opened "This PC" to see which hard drives were showing up, and it totally froze. It then restarted and got stuck on some stage of start up (I think it said "Loading Operating System").
So I then plugged the old hard drive out, and left just my main hard drive for that PC plugged in. But when I turned the PC on, it went to the Windows logo and bluescreened with an "NTFS FILE SYSTEM" Error,

At one stage it also went through a whole "Repairing" procedure.

Please help, I hope I haven't lost all my files etc....