I had plate and screws in my ankle when the boot comes off my foot around the wound and ankle is numb to touch why would this be and is it normal?

Could be: Some numbness following internal fixation surgery is normal. The cutaneous sensory nerves can return after some time. However, depending on your specific injury, there may have been nerve injury during the trauma or surgery that is irreversible. See your orthopedic surgeon for more details.

Yes: It is not unusual because surgery interupts the nerves in the area.