phone working but display not working properly

actually my iphone 3g got totally shutdown due to charging... its not get charging again bcoz.. battery had nil power. so i opened my phone and kept for battery charging... then i fit it... lateron its working as old.. but i dont fix the power but as it position.. so got little prbm with that button.. so i reopen the my phone agian.. i fix all my prbms.. but big prblm is born... that is disply is notworking.. but calls are coming... so i again i opened the phone all strips are same placed.. all r in right posion... so how can i rectify my prbm.... plz sol.....