if you don't have backups you can try to ask to the hosting company if they can restore a backup of your website/database for you. Usually all the hosting companies take backups for a variety of reasons, but it's your responsibility to maintain your own backups. Have you checked if the content is still in the db? maybe they just screwed your website frontend so that the content doesn't show up anymore.
Most hosting providers do sites backups on a regular basis, so check with your hosting provider. Good Luck!
If you haven't been able to find a backup (or even just in case) before time runs out you should do a search within your forum url via google "site:yoursite.com/forum" and copy and paste the discussions from googles cached results if they're that important. At least you'll have a static copy if nothing else.
That is if the Host does a backup Some "Say" they do but when asked for it, it don't come.. Seen it many time's... But do ask your host for a backup and hope they got one! Yes this is why i backup everything one time aday...
This is the best answer. The hosts usually backup periodically, but you'll lose a lot of content if you don't have your own home backups.
check your database first. if entries are deleted from database, they will be lost forever or sometimes web hosting automatically saves whole database after some days say 10-15 days. if such database exists , they can retrieve their posts.
And remember to do it quickly before the Google caches update. I had to go through this process before when I lost a lot of database entries and it turned out the hosting back up plan I actually kept backing up to a corrupt archive. Managed to retrieve a lot of info, but not all. And it was a big pain in the behind.
talk to your hosting provider and also with domain registrar. if you contact earlier then chances are you gonna get your secret info, otherwise you will not get that.