I deleted an user accidental
 

Is there any solution to restore a deleted user without forum backup?
Because user post are in the forum, but user not exits...

Thx

Br.: Teufel

No. Deleted is gone forever. If you have a DB backup it will mean a restore, and probably mean loosing some stuff posted since the backup was done.

To preserve what exists, without doing a restore, you will need to create a new account for the deleted user, then reallocate all of the old posts back to the new user. If there are not many posts you could use [Change Threads/Posts Owner] mod to go through the posts and reallocate. If there are lots of posts, you will probably need to start running update queries directly. Never done the latter myself, not for the feignt of heart.

Take a FULL backup before you do anything and test it on an offline server to make sure everything works as you expect. Then take ANOTHER backup after closing the live forum BEFORE you do anything on the live site.

If you make a mess, you have the backup to fallback on.

Hope this helps to point you to a possible solution.