No real difference. You need "play" in #3.
Student or Learner
I have a question.
1. When I was young, I could play the piano.
2. When I was young, I played the piano.
3. When I was young, I used to play the piano.
What's different between 1, 2 and 3?
Last edited by chingchangchong; 13-Aug-2014 at 04:33. Reason: mistake
Sentence 1 suggests to me that you have lost the ability to play the piano. "I could play the piano" = "I was able to play the piano". If you tell me that you could do something when you were younger, I would assume that you can't do it any more.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.