Automatic transmission not accelerating

Hello, there, thank you for this chance to ask my question.

I was driving my car one night when I hit an island which I did not see when I looked over my shoulder for an oncoming car on the passenger side. My wheel cover flew in the air, but I was able to continue driving and get home safely. I did not see any physical damage to my car when I got home, but after about a couple of weeks, when I was driving the car, it would not accelerate to higher gears but was stuck in the first gear. Was the automatic transmission damaged by my hitting the island? Can it be repaired or should I replace it?