Problems with sound mode, home button, messages app, and the button that closes all apps

[Clorisia]

Sound mode: my phone is currently on sound mode but it recognizes it as only being on vibrate mode it will not ring at all.
Home button: for some reason currently the home button does not work.
Messages application: for some reason randomly half of my screen will disappear and I'm unable to see the bottom half of the screen.
Close all apps button just left of the home button: for some reason it has stopped working.
Does anybody have an idea how to fix all these?

 

[BuckyBadg]

Since I'm not sure it is easily fixable, the phone should either be brought back to your carrier's store, or discussed with Samsung assuming it is still under manufacturer's warranty.