sms tone stopped working

[dokdok]

my sms alert tone has stopped working suddenly now i don't here sms's when they come and i have to check my phone every min

 

[Skull One]

Check your alert tone, volume and mute switch. One of them is proably set the wrong way.

 

[dokdok]

I already checked all sound settings and buttons i can hear the call tones ringing but the SMS only vibrates