If the lock cylinder in the drivers door of your 1993 GMC Suburban does not turn the lock cylinder will need to be replaced, you may need to remove the outside door handle to replace the lock cylinder. If the cylinder turns but nothing happens then chances are the lock rod has become disconnected inside the door. In any case, the inside door panel will need to be removed the see exactly what is wrong.
it's the lock tumbler usualy the left side goes first but theres always an exception. not an expensive fix can be done for under a $100.00 by dealer or less by owner not a hard job just a lot of little things