Rear License Plate

Quick Question.

I recently closed my trunk and my rear license plate literally fell off. The screws are still attached, the brackets that fit into the back plastic backing have worn and cracked and now there is nothing to attach the license plate to.

I was wondering, how can i go about replacing this backing? Do i need to go through the trunk to take it out?

How much trouble is it to get this thing out and get it replaced?

Thanks.