Looking at your site it shows it stops just before the footer starts. Can you remember what you were doing on the site roughly when this started happening? Were you putting anything new into the footer area?
The debug shows that there's 18 third party plugins active, so first thing to do would be to deactivate those to see if any of the missing content comes back. If it does, then it will be a case of turning each plugins on/off to see which is conflicting.
Your debug also shows some other issues which would might want to check out with your host as some of the below are deprecated php features, you also have ajax disabled which some plugins might use.
Ajax disbled : Yes
PHP Magic Quotes gpc : Yes (bad)
PHP User : Posix functions are disabled on this host!