If you die, you lose all your stuff. You keep your Class(es), Race(s), and Level (and any Curses that were affecting you when you died) – your new character will look just like your old one. If you have Half-Breed or Super Munchkin, keep those as well.
When the next player begins their turn, your newly revived character appears and can help others in combat with your Level and Class or Race abilities . . . but you have no cards, unless you receive Charity or gifts from other players. On your next turn, start by drawing four face-down cards from each deck and playing any legal cards you want to, just as when you started the game. Then take your turn normally.
Once you have died, you don’t have to Run Away from any remaining monsters.
Dead characters cannot receive cards for any reason, not even Charity, and cannot level up or win the game.