I am stuck on 1 conversation on messages. I can't go back to my othersu

On my IPhone 4s, it says I have 11 message notifications. When I click on the text message Icon, it takes me to the last person to text me, my buddy Josh, and when I click on "back (11)" in the top left hand corner to look at my other messages, it kicks me out of the app and goes right back to josh when I click on the text icon again. Anybody have any ideas how to fix this? Restarting the app didn't work, restarting the phone didn't work, I'm lost.