I feel pain in my eyes after using laptop n mobile for like 4-5 hours. its started few days back. my hairs are also starting to fall. wts the reason ?

Unrelated: I would think the hair falling out is likely unrelated to the eye pain. There are many reasons hair can begin falling out from vitamin deficiencies to hormonal imbalances to normal aging. You are likely experiencing eye strain with the constant computer use, if this persists I would see an eye doctor to evaluate your vision. Otherwise, take rests after every hour, maybe 15 min at a time.