SOME OF THE REASON FOR A CRYING BABY'S ARE:-
1.Hunger :-If three or four have passed his last feeding

if he has just woken up or if he has just had very full dipper and he being to cry.he's probably HUNGER.
2.TIREDNESS :-  Look for these signs:- descresed activity,loosing interest people and toys, rubbing eyes,and the most obvious, Yawning.If you notice any of these in your crying baby .it's means baby wants to sleep in slice room.
3. Discomfort :- If a baby is uncomfortable in too WET, HOT, COLD, ARCH HIS BACK.When he cries then try to get away from the source of the discomfort.Try to finger out what's causing his distress and solved the problems.
4. LONELINESS :- If your baby falls  asleep feeding and you place her in her crib.but he wakes soon afterward with a cry.its means his feel Loneliness.He want to your warmth.
5.  COLIC :- if your baby cries incosolably for long period every day.he may have a problem with Colic.mostly baby's have a colic problem in the starting  1-3 months.After that his digestion will strong and Colic problem has gone.