help? cd player, clock, etc dont work

A few weeks ago I accidentally left my keys in a friends car who lives over an hour away from me. My brother said he could start my car by hotwiring it, and i stupidly let him. well he got everything back to normal and i got my key but now i have 4 problems ive noticed

1)CD player doesnt work anymore
2)the little clock wont display
3)it doesnt beep if i leave my lights on and open the door
4)the airbag light stays on now

is there anyway to fix any or all of these problems? i'm trying to sell the car and im afraid this'll make it less desireable

thx.