just to clarify
swapping the hard drive will ensure the data on it REMAINS AS IS ...
a FORENSIC copy will be a VALIDATED copy, so if the Co suddenly find 'evidence' on your drive, you can access a complete copy to see if it really IS there ............

REALLY listen to Undies

but get the drive OUT
get your legal team to clone it
get a PC repair crew to rebuild your PC, as you are not au fait with PC's

repairing the PC is NOTtampering with 'evidence'
the 'evidence' is on the drive

and I repeat
read and digest all the posts given in answer so far