My sound wont work! Help!

[neoshebet]

Ok so I have my media volume and my ringtone volume all the way up but the sound on my videos don't work even tho it worked earlier. How can I fix this? Should I return it because my warranty hasn't expired?

 

[Xerozix]

Restart the phone.
Long press of power button
Select Power Off
Long press of Power Button
Let it boot.

You should be back to normal