There's currently three problems with the forum.
1. It is running on a PHP5.x server with a altered version of the phpbb2-forum software called Przemo
2. Somewhere on august 25, there was a crash that caused the forum to stop working. As a result, two tables are completely gone from the forum database. I'll explain this later.
3. The posts-counter has been reset to 0. I will also explain this later, because it has a correlation with 2.
Ok, how to solve these problems?
1. Running the Przemo software on php7 is not possible. Upgrading from phpbb2 -> phpbb3 seems like the only possible solution, phpbb3 is running on php7.
phpbb3 offers an option to import your phpbb2 forum data to phpbb3. I've tested this and as a first result, it seems to be working okay. Of course, there's the usual UTF-8/unicode problems (diacretes, emoji's, etc), but I think that is something I can overcome. Logging in works with my zoolook.nl account, so user data works, and I can see my private messages too. Jay!
2. The missing data. This is the real problem. All topic data is gone and all post data is gone. However, and that's a bit of good news, all the post text still exists.
What does that mean?
Well, if you look at the board hierarchical, you have the following structure
Forums -> topics -> posts -> posts text
This is how it is modeled in the database too.
The forums are News, Oxygene, Articles, etc. Within these forums there are the topics, with in the topics there are the posts.
You can see the forums just fine now, but all the topics are gone. The topic table contains (amongst other things) the topic title and a link to which forum it belongs to.
The posts table is similar, it has a reference to the topic it belongs to and a reference to the forum it belongs to. A bit of redundancy there. It has also a user-id of the one who posted, a datetime value, and many other things. But the posts table does not contain the posts text, that is stored in a different table.
This means there are a bit more than 200,000 orphaned posts. And judging from the highest forum-ID, it is also missing 7,000 topics.
I've tried to get a backup database from the webhosting and it turns out they have a backup of maximum of 7 days old. That means we're a few days too late. This hurts, of course.
Beatle is going to look if there's a backup somewhere on a local disk, but we don't know if there's one and if there is, how old it is.
I've tried to figure out if data could be restored by using some redundancy values, but there's too much data lost. If the topics table only was gone, you could restore it quite easily.
3. I've reset the auto-increment number to the latest post + 1. That should work, I hope. We'll see when I post this message.

Okay, now for what to do next.
I will focus on restoring the topics and posts. If there's no backup, we will have a problem, but I think all is not lost. Firstly, we always have the posts text, that is not gone. I'm hoping people have this forum mirrored somewhere. So if there's someone who has downloaded everything from this forum, let me know. I might restore data from the HTML fiiles.
In the meantime, I can try to port the data to phpbb3 without the utf-8 problems. My deadline for a 100% correct port is 15 september.
Any suggestions and ideas are welcome.