Can't access my Apple Account.

Some time ago I changed my cell number and as a result I could not access my Apple Account or any other account such as Microsoft or Yahoo because those accounts were tied to my phone number. I had to create a new one. Now here's my problem: I just now tried (once again) to access my old Apple Account and when I was prompted to enter my verification telephone number, the last 2 digits of the phone number Apple displayed was not even my old number. Someone else has taken over that account. What can I do to recover my account? Help!!!