Why wont your toilet wont drain?

Based on the limited data in the question:-

If the toilet flush is working in that it cascades water in to the pan then the flush IS working. If the water in the pan is not flushing away and the bowl fills with water and is slow to empty leaving waste in the bowl then you have a blockage behind the "S" Bend and in to the stench pipe that carries the grey water from the shower and sink away.

Common Causes;

Sanitaryware caught in the bend and waste pipe.

Toilet cleans which have plastic or metal fixing to the bowl broken free and flushed (caught)

Toilet wipes etc caught on a breaking pipe join

Card from a toilet roll flushed and jammed

All of the above.

It might require the bowl to be removed checked. - You can by proprietary toilet unblocker liquid. However, tis can be dangerous in the hands of someone not conversant with the effects

You might need a plumber with a jetting system to break up the waste.

If the flush is NOT working in that it does not cascade water in to the pan then there are a number of causes;

Handle from the flush to the siphon is broken or unhooked from the siphon

Lift rod to the siphon has snapped

Diaphragm inside the siphon has spilt causing loss of water lift

Ballcock is jammed and not filling the flush/Inlet value on the ballcock is jammed stopping the water fill.

Corrective options;

Take the lid off the flush and check its filling, If not check that ballcok is not jammed, check the valve is allowing water through - if this area is the issue replace the upstand and ballcock

Handle has snapped from the uplifter on the siphon - - replace the handle of connecting hook

Uplifter rod broken/ water not being lifted (damaged diaphragm)

• replace siphon