My home owners insurance claim was denied, what should I do

My roof was damage by wind ,shingle came loose ,many leaks developed and destroyed the interior of the ceiling also with water damages.the extent of the damage is major.initially the insurance company did what they suppose to do by sending an adjuster to estimate the damages, that was in 2015 of last . I waited for a month and half for a response, finally they send a denial letter denying the claim.