Women in Technology

I was doing the tutorial when I arrived at the
point were it said to write
sudo chmod g-w /

this didn't work apparently because I couldn't receive mail.
So being a curious rather reckless learner with nothing to lose I tried various other things. I eventualy (not knowing what I was doing albeit I now do) I tried various variations on the above command.

Then I wrote:
sudo chmod -g-w /

Yes I know it wasn't smart but i'm reckless, so the computer decided that if no one was to have privleges I should be seeing the desktop at all, so the screen went blue and I was forced to reboot in os 9 on my second partition.

Now i obviously can't reboot in os 10 because once it loads it cant login in as a user (neither my account nor the roots because all privileges were erased).
I would like to know if there is a way to regain control over my partition or recuperate the data while in my os 9 partition without using data recovery software?

Thank you

Severin Smith