OK easiest answer is if you don't hear the fuel pump prime. Then suspect bad fuse or pump. Check fuse box either in car or under bonnet (hood). If fuse is good, chance are your pump is bad.
It can only be one of 3 things, fuel, air or spark!
Air isn't the issue, spark probably isn't the issue. If it is a fuel injected car, turn key on as you would to prime it, then turn off. crack the nut on the fuel hose to the fuel rail, start undoing it, if no fuel comes out. Bad pump, if fuel dribbles out but not under pressure as it should be, bad pump. Change out pump. If fuel comes out under pressure, tighten nut. Turn ignition on, as you would to prime pump, then off again.
Wait ten to 15 minutes. Then crack that nut again, should still be pressurised, if not bad pump.
If pressurised, then your pump is prob on the way out or just silent. Check fuel filter, could be clogged, change it out and try to start, if starts. I'd order a new pump anyway. If doesn't start, bad pump.