a newborn baby cries because everything is new for him and he or she is unable to say or express..
a small child cries because of not getting his or her required things..
a teenager's cries because of scolding or beating..
a grown up child cries because of borden of studies and fear for future...
men or women cry for their sacrifices emotions friendship parents and love...
a middle aged person tries for the welfare of the family for job and for his health...
an old person cries because he has fear to die and leave his beautiful world...

soooo.....

different people have different reason to cry But one should never show his ears to anyone else without tears life is impossible...