The heater in my central heating is not getting turn on but the fresh air and cooling is getting turn on

Thermostats don't actually blow anything, the heating system might though. Check the breakers for your heat system, then call a heating specialist. They're really not that expensive.

thermostat neeeds to be calibrated or one of your 1st stage heating elements bad.

Did you bleed the air from the pump .

What kind of water heater do you have?
In any case, it sound like a plumber should check out system.

Do you have indirect heater that gets heat from central heating boiler?
Most indirect/boiler combo heaters have control that is set to heat the water first.
If water is not getting heated, then the control needs repair.

Do you have gas water heater with gas central heating?
The central heater may be drawing so much gas from meter, that other gas appliances are unable to function. larger gas meter or gas line may be needed.
Or if furnace and water heater vent on same chimney, the backflow from central heat could be affecting burner on water heater especially if water heater has electronic sensor that stop combustion if air quality is bad. Venting problems can lead to CO poisoning, and are a serious matter.

The Cold Air Return is really the Return Air. The Purpose of the Return
air duct is to pull the cooled or heated air back to the furnace. It then
filters the air before getting cooled or heated again.

This is what controls the thermostat, which starts and stops the unit. In
the end this is how your air stays conditioned. In some states it is
required by law that a 4-6inch fresh air vent be tied into the return air
duct. Everytime the furnace fan comes on, it pulls in fresh air from
the outdoors.

yes it is normal. the blower continues to run after the heat turns off to cool the system down.

Sound like there are running on emergency heat which is elrctric.Have the system checked out buy a local heating and cooling company. Have they checked the filter and changed them.

the tstat sounds like it is not connecting the white and red terminals which is usually the heat cycle if it is a gas furnace if so to check I take tstat cover off and jump white terminal to red terminal this is the standard heat position the unit should fire the heat cycle if not a gas funace let me know what type of unit you have hope this helps

Need to have checked out by a diagnostic ac man.

Sounds like it may have lost power. Check the breaker and the fuse at the furnace. If they are all in the on position and working then it sounds like you may need a technician. If the display is blank on the thermostat you may also want to replace the batteries.