Accidentally set Finder sharing and permissions for everyone to no access
I have a relatively new MacBook Air. In reviewing the sharing and permissions settings for the Macintosh HD and for user known as "everyone", I changed the setting from "ready only" to "no access" thinking that this would block access from other users (like other family members). Well, it did, but I'm part of "everyone" and now have no access to my Air.
I have tried rebooting and accessing Safe Mode (Command/Shift/V) and I can see the status information as the machine tries to lauch in Safe Mode, but then the screen turns white leaving me with no interface through which I can launch Finder and correct my stupid mistake.
I welcome suggestions. Thanks in advance.
Tom
MacBook Air, iOS 5.1