New HD, Lost access to old files

Original hard disk running XP Home suddenly stopped wanting to play so installed a new one and loaded XP Home onto it. So now the pc boots XP home from new HD (C) no problems and i can see the old HD (D) but when i go into the doc & settings of the old HD i can only open one users folders and not the other two.
Previously i had two user accounts with passwords and one without, obviously the one without i now have access to and not the others two.
Does anyone have any ideas on how to "reclaim" access to these documents.

Anyones help or advice will be thankfully received.