Whe I try to edit the text it gives me an message that says "All or part of the selection has no aviable system font. You cant not add or delete using the currentky selected font."
If you think that directly edit text in a pdf file, its not possible. There is no way to edit text in a pdf file directly but don't worry you can easily edit text just go through the following links http://www.labnol.org/software/edit-pdf-files/10870/