1. A booting method capable of executing a warm boot or a cold boot in a computer system when a CPU (Central Processing Unit) crash occurs, the computer system having a CPU and a memory, the CPU controlling the memory, the memory storing data and predefined values of the computer system, the booting method comprising the steps of: (a) causing the computer system to detect that a user wants to execute a hardware reset function or a software reset function when the CPU is in a crash state; (b) rebooting the CPU by executing a hardware reset operation; (c) deleting the data and predefined values of the memory to make the computer system return to a default state when the user chooses to execute the hardware reset function; and (d) regarding the hardware reset operation as a software reset operation when the user chooses to execute the software reset function, wherein the computer system holds the data and predefined values of memory to make the computer system return to a setting state before the CPU crash.