I have a 2007 impala my trunk won't open and my seats Dnt fold how can I get to the trunk to change my tale light

On that model the only way to access the trunk when the latch has broken or has malfunctioned is by removing the entire rear seat assembly.
You need to pull the bottom section(the part you sit on) of the rear seat up and take it out of the car. Under the back section of the seat you will find a pair of bolts that hold the upright section of the seat to the car body. Remove the bolts and lift the seat back section up and remove it. Remove the protective layer and you can crawl into the trunk. You can then access the trunk latch from inside the trunk.

The vehicle should of course have been engineered with at least a narrow center fold down section of the seat from where you can access a manual trunk release . No doubt as a silly cost saving measure it was not designed this way.