Benz C320 2002 All Of A Sudden, Won't Start

The car was running just fine all day, i even got a flat
tire in the morning and put a spare on and
everything ran fine. No problems starting up until i
got home, went inside and came right back out to
start the car again. When i turn the key, all lights
turn on correctly as if the battery is okay. When i try
starting the car, it sounds as if it is trying to start,
but shuts off soon after. There were no problems
with the car besides a shaking sometimes when
breaking as well as when backing up. Dad and I
thought it was the fuel pump, replaced it, and no
change at all. Any information could help!!