Drive permissions problem - I can't access it!!!

Hello everyone!
First, thank you for all great posts from here, they are very useful.
Second..i have a big problem. I use Windows 7 Ultimate and today i tried to change file permissions for a drive from my HDD and removed the group "Logged in users" by mistake.
Now my drive is unaccessible.
Also, the Security tab from properties dissapeared.

Anybody can help me in this isssue?
I would be grateful to you.

many thanks,

This website is not affiliated, owned, or endorsed by Microsoft Corporation. It is a member of the Microsoft Partner Program.