Important Help! Upgrade has destroyed my forum!

themoneytank wrote: I would try to restore the forum with the backup, but i cant find instructions anywhere on how to do this. ...

Do you know what the best thing is to do please?

Thank you for your reply and, again, I'm sorry to hear that it seems you had not made adequate preparations for K 1.6 (such as reading the "read me" instructions beforehand) before you went straight into the upgrade. The situation should, however, still be recoverable.

Try this:

Go through the installation again;
Select "Downgrade to K 1.5.x" (whatever the version was that you previously had running)
That should get you back to where you were.

Let us know if this helps.

EDIT: I started to write my reply a long time ago and I had other business to attend to in the meantime. I'm pleased to hear that you were able to go back to something that works.

You should be able to upgrade: make sure you choose the "migrate" option next time. But, before you do anything, backup your system. There are many tools to do this (one is Akeeba Backup)