Q: Admin changed to standard on 10.8.2 updated and have serious permission problems plz help can't access most of my data and make changes

1. Restart holding down the Command and R keys.

2. You’ll be at the Repair Utilities screen. Click the Utilities item in the Menu Bar, then click Terminal.

3. In the Terminal window, type resetpassword and hit Return.

4. The password reset utility window launches, but you’re not going to reset the password. Instead, click on icon for your Mac’s hard drive at the top. From the dropdown below it, select the user account where you’re having issues.

5. At the bottom of the window, you’ll see an area labeled Reset Home Directory Permissions and ACLs. Click the Reset button there.

The process takes permissions Home folder a few minutes. When it’s completed, restart.

If you still can't change it in System Preferences > Users and Groups by unlocking the lock and checkmarking "Allow user to admisitrate..." all I've got is this archived article... be sure you have a good backup before you attempt it.

http://support.apple.com/kb/TS1278