Should I be concerned?

[WJTED1]

So it began with white smoke coming out of the exhaust. Then on the highway it died with a odd noise. So thinking that this was a valve or something really bad I decided to take out the motor. While following the steps and getting close to removing the mounting bolts I found the spark plug had come out of the mount. So I put the engine back in and now it does start but it is as if I don't have a muffler. It is loud. I took the pipes out and remounted them and it "seems" the sound is coming from the middle of the exhaust assembly. There are no holes but I can't figure where the sound is coming from? The concern of this post is the spark plug coming out? Thanks for your time!! Oh it's a 2009.