Go to the Mach3 folder where you will see a folder called xmlbackups, look for one with the same name as the profile you use and change its file extension to .xml instead of .xb** then copy and paste it into the Mach folder overwriting your current profile. Each time you close Mach a backup is made so you may have quite a few, probably looking for one with an early number would be better for you.
I think however it may be more a drive issue, have you changed any dip switches or anything on your stepper drives recently?
Hood