In order for folks to help you, you need to give more information. What is her registered name? What is her barn name? Color and markings, pictures would be helpful? How old would she be now? Was she a show horse, what events did she go in? Who did you sell her to?
Have you tried contacting the Arab registery with her registered name? They might be able to tell you who her current owner of record is.
Good luck.
Spotted Pony