Make sure you are in park or neutral for the automatic transmission (wiggle the shifter or move it back and forth a couple times...), and the clutch is securely depressed for a manual. The starting system will look for neutral or park or the clutch being depressed before it will allow the signal to get to the starter. With not even a "click" from your problem description, that's where I'd start.
Beyond that, you could have a battery cable issue (loose, corroded - at the battery or the ground or the starter...), you could have a starter relay issue, or a solenoid/starter issue. If you try to have the car jump started, will it then start?
You could even have a basic battery issue, even with lights on, you may not have enough power to get the starter motor turning.