Apps can be pulled for many reasons, Apple may change their Rules on what they allow and may pull the app or the Developer may also give up on the app himself.
Do you know who the Developer was...getting in touch with them may be the best way to go.
The IPad Forum is a community of members from all walks of life and from all over the world coming together to share our experiences and to help each other learn about this wonderful piece of technology the Ipad. There is a wealth of information already here in the many threads we have so doing some searches will answer most of the questions you have. If then you cannot find the answer you are seeking then by all means post your question. There are many friendly and informed members here only too willing to help you.