Hi,
It is a little difficult to help without knowing certain things - I assume you are studying media? Is that why you have chosen this topic?
Did your advisor suggest you didnt do this topic at all or was she asking you to re write your proposal so you could defend it in terms of the questions she was asking you?
Choosing your dissertation topic and writing the proposal is almost the hardest part of the whole thing! It has to be written in a certain way. You also need to back up your proposal with plenty of evidence of where you are going to get the primary and secondary information from. This also helps you to decide if it is acually feasible to do the study in terms of the amount of info you will find to do it.
This is a good guide for content if you decide to stick with the topic but just need to re write the proposal!
http://www.graduate2b.co.uk/dissertation_advic e/sample_proposal.htm
Hope this is a help, good luck with it all!