Is it old enough to bloom yet? If it is blooming, are there any bees to pollinate it? Some varieties also need a different variety nearby to provide the pollen. Bad weather during or right after bloom can prevent fruit set, as well, as can an ill-timed application of fertilizer.

If you have a solitary pear tree it may not be self fertile, some are, some need a pollinator nearbye, say in a neighbours garden. If you know the name of your tree. Then type the name + pollinator into Google and you will quite easily find a named tree that matches your tree. Happy hunting.