WinXP File Permissions – Can’t access a file

I was tightening permissions on a folder in a shared machine and I typed something unknown (thumb-fingered). I managed to get the folder back, but I can’t get into the MS Access files in the folder.

The OS is WinXP Pro SP3. General properties of the file, including size, come up fine. Security properties yield no info except the following security message:

“Security: You do not have permission to view the current permission settings for , but you can make permission changes.” I click OK and I see the Security info with no group or user names permissions grayed out and not checked.

When I try to add a single user group (I’ve tried System, Users, and Administrators) I get a message that says: “Unable to save permission changes on . Access is denied.”

I am researching the web, but haven’t found much so far. I did check the root permissions in the registry files and they seem ok.

Thank you for any time and help you can spare.
Regards,
Bob

Edited to regain punctuation