My car won't start, I've already changed the fuel pump, crank shift sensor, cam sensor and now I've been told I need to change the gas regulator but the security light blinks when I turn the car on.

My first thought is no because if the crank or cam sensor were defective then starting fluid would have no bearing on the engine starting. I would think faulty fuel related problem like fuel pump, fuel regulator etc. Hope that helps

have you changed the fuel filter and emptied the gas tank and put fresh gas in? Stale gas will not start as well as fresh gas and there could be water from condensation in the tank.

P0750 is the trans shift control solenoid valve A , P0755 is shift control solenoid valve B .C0701 can't find the trans codes wont keep engine from running. If crank sensor was replaced it should be ok it only tell witch two cylinders are up. The cam sensor tell witch cylinder is at tdc to fire. Check for fuel and spark , if both present check map/maf sensors tp sensor then ecm/pcm.

run the fault codes and check for cam/crank position sensor . check that the cam shaft is turning (broken cam belt)

Sounds like your fuel pump in on it's way.

What you are telling me is the engine is firing the plugs but not getting fuel.
When you changed the fuel pump and filter, did you check the fuel pressure at the rail ?
Are the injectors getting power and ground pulse ??

First, check the condition and operation of the following:

1) Spark plugs, leads and coil(s)
2) Air filter
3) Fuel filter and pump operation.

Check your cam and crank position sensors. Check the fuel pressure regulator and then the Fuel pump itself. This sounds stupid, but go check the gas cap too and make sure it is on tight. Sometimes it's the little things..haha. The two sensors tell where the crank and cam are in relation to each other and TDC of Piston 1. If one of the sensors is out of whack...the whole timing process will be thrown off. Most of the time if the cam sensor is bad, the car won't start, if the crank, it will start but run like ****. They don't cost much usually and your car is old enough that they should be replaced anyway. The MAF sensor would just cause the car to run rough most of the time if it were faulty or dirty. But being how generalized those codes are, it's never fun to figure out. Hope this helps you :)

First check where your fuel pump relay is then check it or have it checked to make sure it works proper. Then check all fuses in the auto to make sure all are good. If after all this checks ou and still no fuel pump sound from the tank if you stick you head close to the tank the pump can be heard. If you do hear a pump running this could be a sign your fuel filter needs changed it is clogged up. if no sound pull the fuel pump and supply 12V power to it on the ground away from the car and gas tank and after it has properly drained of fuel and dried. If this pump works on the ground you may look at your cam sensor. If while you are cranking your car and you see the rpm gauge move this means the cam sensor is reading if you see no movement at all change the cam sensor. Often when the cam sensor goes you may as well change the crank sensor as well to prevent repeating the down time of your car later on down the road.

If you haven't done so already, have the cam and crank shaft position sensors checked, or replaced, You have replaced everything else.