Mine does that from time to time.  Try turning off everything - the lights, the radio, a/c /blower motor, and so on, then starting it.  If the battery isn't putting out enough voltage to trip the relay attached to the clutch pedal sensor, nothing happens.(also try pressing the clutch bypass switch)   In my case, it's a combination of cold weather, older battery, lights and radio on... so I'm just in the habit of starting it with all of that off in the winter.