Volume up Button Automatically Pressed

Hello, for 1 week, my high volume button remains pressed and turns up the sound. This had happened to me once before but it stopped on its own after 2 hours. Now it does it but it doesn't stop even if I restart and moreover as soon as I start my phone it puts me in the recovery menu, so it must be a hardware problem. Should I change my volume and power buttons to fix this problem, is it hard? Where can I buy ?