oh...

and what does that mean?

haha

That does mean that you have to put your table prefix in front of user, userfield and usertextfield in the queries I posted :)
I don't know what your table prefix is - you must know that as it is your installation.
(Can be found in config.php => $tableprefix)

$tableprefix = 'forum2_';

Then put forum2_ in front of user, userfield and usertextfield in the queries I posted.

ok, i did them all...

and they all worked...

now he is userid 509... but how do i assign all of those "guest" posts to that username?

ACP / Import & Maintenance / Update Counters - if the posts still carry his userid
If not you must assign it.

yeah, the posts no longer carry his userid...

his name had been deleted...

and i can't do anything to a "guest", can i?

Then
[sql]update forum2_post set userid=509 where username='D.'[/sql]

You must also do this for Threads, PMs and Usernotes

oohhhhhhh....

you are the man, kirby! :)

hello Andreas

and tanx for your good guide for this important problem
i has same prob and i do from your posts one by one. now my deleted user is alive again and his posts are linked to his name and user name... but some problem:

1- what do you mean "You must also do this for Threads, PMs and Usernotes"
I put "Threads, PMs and Usernotes" in place of "post" in your last SQL Query but it has error and say the thread have not user name or something like this

2- His number of posts and thanks and thanked and ... is still 0 from wher i can update them. i was update some thing in ACP but not effected!

thank you very much