Honey that has been treated with heat where all the microbial properties have been destroyed will never candy.

Honey candying is a natural process as a result of the honey containing natural micro particles of wax and pollen cool. 

This does not mean the honey has turned or is unsuitable for human consumption, and you should not dispose of it.

If you place your jar of honey in warm water it will gradually return to its original liquid state. You can repeat this process a number of times if required.

Do not microwave the honey as this will destroy the microbial properties of the raw honey, and heat inconsistently, and has a risk of overheating.