No sound on any app/function iPhone 5

Hi guys i got my iPhone 5 about 2 week after launch and about 3 weeks later i lost all sound clicks from text's, game apps, YouTube wouldn't play any videos and it worked perfectly fine when i went to bed wake up in the morning to this.

I rebooted the phone and this resolved the issue, the phone was not in silent mode via settings or via the slider at the top of the phone.

the phone would be working fine for about 3 weeks then this would happen again same issues as above this went on till about the 14th December and Apple decided to change my phone now its happening again.

I am at a lose end does anybody know a fix or heard of this before as i am sure this problem could not happen too 2 different phones ?

Thanks