My central heating isn't working. Help please?

Details:
-My thermostat says that I have the temperature on 75 degrees F which is what I want but it remains at 62 degrees F and won't budge
-It's a gas heater
-The hot water works
-No air is coming out of the vents at all.
-I hear a clicking noise in the vent when I turn off the system & then turn it back on

What can I do?

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central heating Aberdeen
combi boiler Aberdeen