as we know worker bees, mules and infertile human couples cannot reproduce .infertile human couples reproduce bye ivf but how does mules and worker be increase their population whereas we know they do not reproduce?

The majority of the population of workers bees are all females and they are beneficent as they take care of the queen at the expense of their ability to reproduce. These worker bees actually take care of the storage cells of the hive and further move on to brood care and food storage and this is how these worker bees indirectly contributed to increase their population.
A mule on other hand is an offspring of an male donkey and a female horse, mules can either be male or female because of the presence of odd number of chromosome they cannot reproduce. So if a mule (female) have to produce offsprings it has to either mated with the purebred donkey or horse.