Driver door no power

check the wiring in the door jamb boot , after 20 years of opening and closing a wire can break .

Agree... But if every electrical device no longer works, it's likely a ground wire. Not difficult to find or fix.

Pop the master control switch component out, however yours comes apart and troubleshoot, It should just pop up if it's the one I'm thinking it is, search '2004 chevy avalanche master control panel removal' online Check the connections and plugs for power in and out, a new switch assembly is around $100 or so, check Ebay. Trouble shooting is the hardest part so start with the easy stuff first, the master switch panel, water and stuff gets in it.