Assuming you can still read data from your old HD copy your <profile> .xml from your old Mach3 folder (or xmlbackups folder) and paste it into your new Mach3 folder also copy and paste your license file, macros folder and any special screen sets you have been using.
If you cannot read data from your old HD then there are many HD recovery software programs available - some work better than others.
Tweakie.