Nokia Lumia 635 lock button temperamental?

So I got it at christmas and its a really good value phone, I don t use it really heavily except when I m listening to music. About a week after getting the phone the lock button stopped working and the only way to flash the screen up to unlock was by plugging in the charger but my friend showed me how to hard reset which makes it work for a few hours but then goes back to not working although even if the lock button has stopped working I can still shut it down (which makes the slightest bit of sense).
Does anyone know any common solutions to this before I throw a 20 at some guy to do something I could do for free, thanks for any help in advance!

Read more: Nokia Lumia 635 lock button temperamental?