Suddenly the screen of my n900 stop responding. i was to my home i unlock the phone , i go to the menu and i was trying to play angry birds , i tap to the icon and nothing , the menu is going up and down but the center of the screen is not responding, i tried to flash , but again nothing , now i have stuck to the regional settings and i can not do anything , i can not press nothing only the edges of the screens are responding . help what can i do?