Set $debug=1 in /conf/_basic_config.php or /conf/_advanced.php and try to analize the debug info.
Do report back to this topic if you find something interesting.

Good luck

I copy it here, because I don't really understand, maybe someone could. I think it's something about blog id.

# debug_die( "Requested Chapter does not exist!" )
File: C:\internet\wamp\www\b2evolution2.3\inc\chapters\model\_chaptercache.class.php on line 126
# ChapterCache->get_by_ID( "1" )
File: C:\internet\wamp\www\b2evolution2.3\inc\items\model\_itemlight.class.php on line 151
# ItemLight->ItemLight( Object(stdClass), "T_items__item", "post_", "post_ID", "Item", "datecreated", "datemodified", "creator_user_ID", "lastedit_user_ID" )
File: C:\internet\wamp\www\b2evolution2.3\inc\items\model\_item.class.php on line 222
# Item->Item( Object(stdClass) )
File: C:\internet\wamp\www\b2evolution2.3\inc\_core\model\dataobjects\_dataobjectcache.class.php on line 156
# DataObjectCache->new_obj( Object(stdClass) )
File: C:\internet\wamp\www\b2evolution2.3\inc\_core\model\dataobjects\_dataobjectcache.class.php on line 302
# DataObjectCache->instantiate( Object(stdClass) )
File: C:\internet\wamp\www\b2evolution2.3\inc\_core\model\dataobjects\_dataobjectlist2.class.php on line 180
# DataObjectList2->get_by_idx( 0 )
File: C:\internet\wamp\www\b2evolution2.3\inc\_core\model\dataobjects\_dataobjectlist2.class.php on line 199
# DataObjectList2->get_next( )
File: C:\internet\wamp\www\b2evolution2.3\inc\items\model\_itemlist.class.php on line 287
# ItemList2->get_item( )
File: C:\internet\wamp\www\b2evolution2.3\inc\items\views\_item_list_full.view.php on line 125
# require( "C:\internet\wamp\www\b2evolution2.3\inc\items\views\_item_list_f..." )
File: C:\internet\wamp\www\b2evolution2.3\skins_adm\_adminUI_general.class.php on line 510
# AdminUI_general->disp_view( "items/views/_item_list_full.view.php" )
File: C:\internet\wamp\www\b2evolution2.3\inc\items\items.ctrl.php on line 714
# require( "C:\internet\wamp\www\b2evolution2.3\inc\items\items.ctrl.php" )
File: C:\internet\wamp\www\b2evolution2.3\admin.php on line 221

Probably
Do you have a backup or have you screwed your database and need to restore as much as possible?
The blogs are numbered from 1 to ... If you remove a blog the number get unused. I think you soved quite a bit if you find out what the original ID numbers were and then assign them to the correct blogs (change the database).
Start in the backoffice and look what number the respective blogs have now. If you find IDs 1 through 9 chances are the blogs are re-ordered. If you removed some blogs in the past, you probably find something like 2, 3, 5, 6, 7, 9, 11, 12.

Good luck

Hi,
finally found my problem. Restoring and adding table one by one and get the faulty one.
My nightmare : categories.
I wanted to add a category in each blog (8) and get it as default. I had some empty number beetween 1 and 15, so I had new items there. (as the lowest category = default) but it cause big trouble.
So how add default category? Keep in mind I have 330 entres and complex hierarchy for each of the 9 blogs. So how I could decalate the number?