Car

Bad battery, loose or dirty battery cable connections, corroded battery cable, defective clutch switch, ignition switch, starter relay / solenoid, corroded or stretched terminal in an electrical connector.

Need additional symptoms or observations to narrow it down. What have you checked so far? Are the head lights bright, dim or out? Are they bright until you try to crank the engine? Have you measured the battery voltage? Have you tried a jump-start?