Sounds not working Xperia SP

[Sgnap]

Hi everyone, I'm writing here as I didn't find anything satisfing on italian forums if not something like "take your phone to assistance". I apologize in advance for my English and hope to be clear enough. About 10 days ago both my husband and I bought a Sony Xperia SP. I started using it 3 days ago, he did only yesterday coz not enough time to set it up before. We used same settings for both and we just downloaded a couple of apps. We installed all suggested updates. Yesterday sounds of hubby's phone (after a day only he used it) stopped working all of a sudden. Ring tones, notifies, games sounds, music and all internet audio contents, all silent, nothing had sound on loud speakers. But strangely everything works correctly with earphones on. What could be the problem? Can I solve it without giving phone to assistance shop for a couple of months (knowing timings here sadly)?

Thanks to all who can help 

[Atthar]

The plug in and out didn't work for me. I tried many times but nothing happened. I read Mcomiskey suggestion using kirby grip (I use toothpick) and it works!