This depends on the severity of the crash. You might consider checking the CALSET of the robot first. 


If your robot arm model has brakes, release the brake of the suspect joint by using a full-size teach pendant and pressing ARM > SHIFT > MAINT > BRAKE, then carefully push the joint to its mechanical stop. (Depending on your robot model, you may need to use a jig to do this, as referred to in the CALSET procedure.)

Next, go back  to the ARM menu and check the angle of the joint; it should match the RANG data for that joint on the label at the base of the robot.