hope somebody can help me.i'm running osx tiger on my iBook g4.a friend did a prank on me.obviosly,he thuoght it was harmless.anyway,he changed the root name on my mac,the home name.i never noticed it.then when i restarted the machine,all the files on my desktop were gone.my settings changed,even my bookmarks in firefox are missing.how can i undo the changes?thank you.

eric c.