Also, try typing the ToolbarReset command...
Should be a default.tb file, not .ws (.ws was V2). It should be in the following directory:
XP C:\Documents and Settings\All Users\Application Data\McNeel\Rhinoceros\4.0
(both of these directories are "hidden" by default, so that is why you may not have found it)
There is also a default_backup.tb in the same directory, in case the normal one got messed up somehow - just rename it by removing the backup part.
PS suggest you update to SR5b...