Does the reset button work when not powered? I'm working on a project and my dad hit the reset button on my Arduino board, unknowingly. If it wasn't connected to any power source or computer, did it still reset? Do I have to upload my code to the board again? Or does the board need power to be reset?
The reset on an Arduino does not erase anything. It merely restarts execution of an already uploaded program. Also the AVR needs to be powered on for it to realize whether it has been reset. 

Every time you power on an Arduino it automatically starts code execution from the beginning of the program in the flash memory.