windows/system32/ntkrnlpa.exe

I connected my laptop hard drive to my desktop pc to transfer some movies, once I was done I connected the hard drive back to the laptop, then I went to go on laptop as normal, until this came up.

File: windows/system32/ntkrnlpa.exe
Status: Oxc000021
Info: windows has failed to load because the kernel is missing, or corrupt.

I have tried everything!! I done start up repair etc etc please help!!