2000 Nissan Altima will not start

I think it is the alarm system, how do you reset alarm?
***May be it is the security system, but I highly doubt it. Look at the LED light for the security system. Is it flashing at the rate of 2.6 seconds. If it is, the system is functioning normally. CLose ALL doors, trunk and hood. Lock the DRIVER door with the key. Wait 45 seconds. Open the DRIVER door with the key. Leave the door open for 45 second. Close the door and open the door. That should reset the system.***

i don't have a remote to the door, what is the code for it?
***There is no code per se.***

Follow this diagnostic procedures. Do not skip a step. I know you install new fuel pump and pressure regulator, but still test fuel pressure at the fuel rail and check for voltage at the pump.

HARD START/WILL NOT START

Check battery and starter.
Check fuel pressure.
Check fuel pump circuit.
Check fuel pressure regulator.
Check fuel injector circuit.
Check fuel evaporative emission circuit.
Check Idle Air Control Valve-Auxiliary Air Control (IACV-AAC) valve.
Check ignition timing and ignition circuit.
Check timing chains.
Check Exhaust Gas Recirculation (EGR) valve.
Check Positive Crankcase Ventilation (PCV) system.
Check Camshaft Position (CMP) sensor circuit.
Check Mass Airflow (MAF) sensor circuit.
Check Engine Coolant Temperature (ECT) sensor circuit.
Check main power supply and ground circuits.

If it is the CMP sensor, it will start but runs badly. If it starts with ether, it is fuel delivery problem.

I would still check the fuel pressure at the fuel rail. It has to be about 45 psi.