<Your database is clean 1.0.4 version? I mean is it possible there is some rest from update process? The same with files?>
Not sure how to check this.
Could be very well some leftovers of the update might be present, even so on files.
If a restore is done, one would presume, the restoration of files AND the original dbase ( i do hope you do have own backups ?; not relying on serverparks (some do some do not have old.).
As long as there is an original backup of dbase, its easy (you only have to have a v1 pack files + plugins, adjust config to use the old dbase and thats that. Looks easy (actually method is). The only real issue you might get involved with is php versions.. (older stuff has sometimes deprecated coding).
Is the present system containing leftovers and no dbase (old ) present than it will be manual labour (and testground).
Checks if yes or no : visual compare > v1 has no media,core,web folder (files folders) Are they present > leftover (but be warned, they might contain needed things like images etc, which were moved during update etc..). As for dbase > added tables like core_media and core_media cat, mail content etc... > if present > leftovers..again carefull.. they also might contain stuff.
Keep (and please backup) ALL before you make any changes, and report back if you have original backups. (all = folders; files +content; images etc.. and dbase > mirror on disc)