1996 Buick park ave locks and interior lights not working

I purchased this 1996 Buick Park Avenue
recently for my son.
It has a few little issues that I haven't been
able to figure out.
The interior lights (dome, curtesy,etc..) do
not have power to them. Also the power
door locks are not working. Not even
attempting to do I'm assuming no power
there either.
Also, the horn isn't working.
There doesn't seem to be any other
problems with this nice low mileage
vehicle.
So, any help on these problems would be
greatly appreciated!
Thanks in advance!!