Could be the esc, but they don't normally go bad while just sitting. Maybe it "forgot" the throttle endpoints. Slide your motor forward so the pinion does not mesh with the main gear in case of an accidental start up, then, power up your TX and move the throttle stick to 'high stick'. With the TX at high stick, power up the RX and wait a few seconds till you here the tones, then move the throttle to the low stick position and wait for the tones, then power off the rx then the tx.

Turn the tx back on with the sticks in the normal position, then power up the rx, wait for the tones, then move the throttle stick and see if the motor spins up. If not, ether a bad esc, bad motor, or a loose electrical connection somewhere causing a loss of voltage.