That really depends on the type of ticket you bought. It can vary anywhere, from "you do not get anything in return" to "you get everything". Unfortunately it is something different for each ticket.
Your ticket came with "fare rules", which exactly explain the cancellation / exchange / refund rules for the specific type of ticket you purchased. I would recommend finding and reading them. They can be difficult to read, so if you can not understand what it says, post the full text here and we can help you.