First, check fuse #2 in the under-hood fuse box. If this 15A fuse is blown, you will have no dash lights or tail lights. If it doesn't look blown, try swapping it with a different 15A fuse to make sure.
If the fuse is good, the other thing to check is the taillight relay, located in the under-dash fuse box. This is the second relay from the left. You can try swapping it with the power window relay (third relay in, offset up a bit) to see if that makes a difference.
Those are the only things it could be, short of a broken wire or all the bulbs being burned out.