Volume on iphone 4s is not working

The volume on my phone is acting weird, i can here the ringtone that plays when i get a call or txt but if i watch a video on my phone or play music and i can't here it. And when i press the volume button to go up it just shows it as blank instead of showing the bars for when its rising. I didn't drop my phone or anything, the volume was working perfectly fine an hour ago and then it randomly stopped working. How can i fix this? Restarting my phone didn't help

Press it harder LOL

First option try going to (settings>music>volume limit) then increase to the max, then go to (settings>general>restrictions>volume limit) change to don't allow changes.