Wow is all I can say about severing the ulnar nerve. I was t-boned in an auto accident 8/30/07. The left arm ulnar nerve was injured in this accident.
After many months of occupational therapy, a nerve conductivity test, MRI's and so on, I had surgery to move the nerve from it's normal position, in front of the elbow to the back, to protect it while it heals. Also had guyons canal release at the wrist , as there was significant nerve irritation in the hand.
All that to say, that the nerve, according to my surgeon, (orthopedic surgeon, specializing in hand, elbow and shoulder) will regenerate at about 1 inch a month. With a typical elbow to wrist measuring 12 inches or so, I should take about a year to regain most of the functionality of the hand and elbow. The fine motor skills in the hand were significantly impacted, grasping, holding, and lots of pain. I am seeing added ease of movement, although, my hand still grows weary far ahead of what I want to do. Sweep floors, type, repetitive motions ... many things we take for granted are repititive in nature.
I can say, that it is slow, but steady in recovery. The slow part should be emphasized here. Did you have surgery yet? I have to assume that you had surgery, if the tendons and nerve were severed. The most important thing to remember is that you will heal, you will most likely never be the same again, but as we age, we aren't the same as we were 20 years ago either. On this side of surgery, (surgery date 2/26/08). I am so glad that it was done. The initial discomfort of surgery is outweighed by the way I am at this point, so much better. I am not trying to paint a glossy picture here, it is important to note though, that my experience, although long to me is a good one.