Is the numbness caused by nerve damage?

I cut my hand at work a day ago below my thumb about an inch long and deep. I went to the hospital and I told them it is very numb but they seemed more interested in getting paper work done for workman's comp. The doctor gave me stitches and I left. It has been over 24 hours and my thumb is still very numb. Is this because of nerve damage? If it is can it be fixed since it has been so long?