I changd my plugs,fuel filter,air filter and battery & checked all fuses my car starts but still won't fire up what is the problem.

If it turns, then the battery is OK. Either spark plugs are not firing in proper order (wrong firing order), no power to spark plugs, or no fuel because of fuel restrictions (dirty fuel filter). Inspect the air filter to ascertain its not clogged air. If you smell gas, then you saturated the spark plugs, which is why it refuses to run.
Let it sit for half hour to let spark plugs dry. Inspect to ascertain its not dirty spark plugs, which will also prevent engine from running. After ascertaining its proper firing order, spark plugs are clean, and there's power to distributor cap, ascertain there's fuel in fuel lines by squirting half second (short squirt) of starting fluid into air filter. Close the air filter housing to trap flammable starting fluid gas. Turn engine without giving throttle. Let starting fluid be ignited by spark plugs. If it won't start, then spark plugs are not firing to ignite starting fluid gas. If it starts briefly, but won't run when you give throttle, but catches when a 2nd person squirts more starting fluid into air filter just before engine stalls, then its a fuel restriction issue or no fuel in fuel lines.

If it's getting fire and fuel would suggest timing issue. Maybe check crank and cam sensors. Getting any check engine light?

First check the operation and condition of the following:
1) Spark plugs, leads and coil(s)2) Fuel filter and pump3) Air filter

check your fuses as a start then check relays and then fuel pressure because the filter could have only 1000 miles on it and have problems with it and it could also be the coil pack died on it .

check fuel pump fuse and relay also the fuel injection fuse and ecu fuse, if they are ok remove the back seat and you will see a cover remove the cover and check for voltage at the pump plug and ground, you hear the pump work if not need new pump

To confirm that is is the fuel pump at issue here get a can of spray starting fluid and next time it won't fire up spray it into the air intake hose of the engine while someone cranks the engine over, if it lights right off then the pump may be the problem. A clogged fuel filter may cause loss of power but seldom if ever a no start.

Are the plugs wet with fuel?
Check for spark. No spark? it may be the ignition module.

Plugs dry and spark present? No fuel?Spray a little starting fluid and see if it will run on that.
Then check pump fuses and for fuel pump noise.

If the engine won't fire up, but your starter turns over, you may want to check your timing unless you have a check engine light on. If the CEL light is on, have the codes scanned.

If the engine won't turn over with the starter or it clicks, have your battery tested at autozone or advanced auto parts. Replace the battery if it is bad. Else, have your starter tested.

If the engine still won't turn over and the battery and starter are tested fine, you may have a blown fuse, bad ignition switch, or a failed relay.

If the engine fires up but randomly dies and starts back up, you either have a failed sensor, failing fuel pump, clogged fuel filter, bad plugs or wires, or a failing ECU.

I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

if you can put fuel in throttle body and it runs. then it is not getting any fuel. check your fuel pump fuse and the relay, if ok, then you may have a bad fuel pump or a plugged up fuel filter. check filter and fuses first. good-day !!

if battery good starters good that still leaves fuel,air,spark or timing you could try disconnecting throttle body hose that comes from the air filter try starting if still no start spray throttle body cleaner in the throttle while someone starts. Do you hear the fuel pump coming on when turning key to the on position. Have you checked to see if it is getting fire to the plugs?