Q:

my baby is 2 n half months old n he is not sleeping not in day n not in night also what should i do



A baby this age should sleep for about 14-15 hours in a 24 hour period. I would recommend maintaining a log for atleast three days where you record all sleep timings even naps as short as ten minutes. Many times babies don't sleep long stretches but cover up sleep as small naps. Health wise for the baby this is not a concern but naturally it is taxing for the parents. The log will help to plan future course of action and we will be able to suggest the appropriate consultant for the same.

Swaddle and nurse him after giving massage and bath he should sleep well.

Angel, along with the sleep log that Somali mentioned, I would recommend Babywearing. Babies when are carried/worn in an ergonomic baby carrier, are snugly worn and they sleep better.
Babywearing helps easier transition from womb to the outside world.
You can try a RingSling or a Stretchy Wraps.
Best wishes

*Sonali
sorry for auto-correct