Apathy is an act of not showing interest in something or just don't care about what is going on around you,this is quite different from depression though it can be hard to tell the two condition apart.It's isn't sadness or anger rather it is when you don't feel much of anything or things that used to make you happy don't excite you anymore.This can affect your job,your relationship,your ability to enjoy life and might make you no longer feel motivated to achieve your goals.
Therefore,in order to fix this you should try doing things you used to like with your love ones,take a music or art therapy class,try to exercise everyday and have plenty of sleep each night,try also to break big tasks into smaller ones so that you can feel a sense of accomplishment and always reward yourself whenever you finish any activity.