No heat

Check the heater core hoses it should be hot if not
flush heater core
Engine cool
lower the coolant level
Locate the two hoses running to the heater core
disconnect them at the engine side leaving hoses connected to heater core throw the firewall
use garden water hose and compressed air if possible
run the water and follow by air throw one side and out the other and vice versa
do that two to three times watching what leaving the heater core you are looking for the good flow and clear water to run throw
good luck
let me know

With the engine warm and the vehicle off, feel the heater core and post back what you find.

Is one hot and one cold?

One hot one warm?

Both hot?

Both cold?

Both warm?

Yes it sounds like it or there is an air bubble caught in the heater core. this guide will help us see what's going on:

https://www.2carpros.com/articles/car-heater-not-working

Please run down this guide and report back.

Change thermostat
your car need a new one

Most likely the fan assy. Has broke or is loose. You will have to take the blower motor and fan out to see what has happened.

You dont have any heat, because you've lost so much coolant that there isn't any in the heater core.

You need to fix the leak or you can damage the engine if it over heats.