Hi! I have problem with my Samsung Galaxy S IV. Sometimes the sound stops working, and then I can't hear when someone calls me, can't hear videos, can't hear anything. Then I restart my phone, but it becomes even worse. It has no sound, i can't run any app. When I run some app, it's slow, and then it says for example: WhatsApp error and just turns it down. Sometimes my screen goes all blue. After few days I restart it again,sound appears and everything is normal. It works fine until sound disappears again. Help,please!