Did you upgrade the OS? Do you need to downgrade that, too?
To just wipe all of the personal owner info and all that, go to Options > Security Options > General Settings > press BB/Menu Button > click on Wipe Handheld.
to hard reset, or to wipe your handheld, got to OPTIONS>SECURITY OPTIONS>GENERAL SETTINGS. Then press the BB key and it says WIPE HANDHELD. This will restore everything and erase everything, but if you deleted a language you won't get it back.
good luck!
