I think my one and a half month baby has colic. he starts crying at 11 pm every night. what can i do to comfort him?

Depends on cause: Babies cry for a reason. Some babies respond to pressure (swaddling), others to motion (swings, rides in the car), some to digestive aids (gas drops, ginger, fennel), some to formula change (to something hydrolized) or to maternal diet change (removing dairy or gassy food like broccoli and beans from mom's diet). Some, for whom you find no cause, respond to homeopathic colic remedies. Try it all.