How do you change the drum belt

possibly the main drive belt has either snapped or jumped off the pulley and this allows you to turn easily by hand the whir/buzz sounds like system in coming into play but with no belt to drive nothing more happens, the front lower portion of the machine could be the water pump working overtime unable to drain ???

Probably a belt broken or slipped off. Does it still whir, as if the motor is running, but the drum does not move? If it does, then you can be certain it is a belt problem. Fairly cheap from your local spares supplier.

Most dryers require the front panel be removed to replace the belt. The belt is a long thin belt the goes completely around the outer part of the clothes drum. Then it needs to be put on the motor pulley properly and the tension pulley. Not something for a novice if you never did one before.

It sounds like the belt is either off or is broken.
Open the door of the dryer and try to turn the drum with your hand. It should be a little hard to turn. If it is reall easy to turn the drum then the belt is either off or broke.

You can take off the top of the unit, and in the middle of the drum you should see the thin belt. It should be tight against the drum.

When you say the thin belt I assume you mean the drive belt.
Hook the new belt on the motor pulley and onto the main drum pulley as far as it will go, hold it on the pulley with a few cable ties. Rotate the inner drum anti clockwise and this will draw the belt onto the pulley and snap the cable ties as it revolves. Use a genuine Hotpoint belt because they contain a carbon fiber content which is designed to counter-act against static electricity, a fault first noticed in these machines some years ago (it can cause the neons to flash and irregular faults to occure)
Click these links for Hotpoint WMA & MW workshop manuals and error codes

Good day,
For the cost, it isn't worth not changing. If it's down, remove the drum and check the rear wheels as well.
P.S. If you remove the drum, after re-installing make sure the felt on the back of the drum doesn't double over for you. If it does, assemble then take a small thin screw driver and as you rotate the drum, roll it back in place.

Unplug dryer and shut off gas. Disconnect gas line. Tip dryer onto its front. Remove back panel. Unscrew and remove inside back manifold. Place belt around drum and fit into pulley wheel(s) on motor shaft. (There may be a spring loaded tension arm on one of the wheels. Install the belt on it so that it pulls the belt tight around the drum and pulleys.) Check friction gasket (that the drum rotates on) on manifold and replace it if worn thin. Install manifold. Install back panel. Reconnect power and gas.

Ignore gas references if electric dryer.
Unplug dryer and shut off gas. Disconnect gas line. Tip dryer onto its front. Remove back panel. Unscrew and remove inside back manifold. Place belt around drum and fit into pulley wheel(s) on motor shaft. (There may be a spring loaded tension arm on one of the wheels. Install the belt on it so that it pulls the belt tight around the drum and pulleys.) Check friction gasket (that the drum rotates on) on manifold and replace it if worn thin. Install manifold. Install back panel. Reconnect power and gas.

Sounds like a broken drive belt. Take off the front cover and look for a long thin belt off the drum or broken in two

Use a turbine oil and oil the center bushing for the belt tension pulley and the center bearings in the rear drum rollers