Audio Problems (underwater/echoing music)

[myCPUsucks]

So earlier today my computer was playing music and sounds just fine. I just went on youtube and watched a few videos with no problems but now my music sounds like parts are faded. It echoes and has sort of an underwater sound. When my music is played through the laptops speakers it plays fine, but when I plug in my headphones the echos are produced. I have an HP 635 laptop. Thanks!

 

[myCPUsucks]

I've looked on google and other sites and tried to fix it myself and I can't figure it out.