The user groups table is ubbt_USER_GROUPS.

If you've somehow managed to remove your entry from the groups table, below should re-insert you as an administrator:
Code
INSERT INTO ubb_forum.ubbt_USER_GROUPS (USER_ID, GROUP_ID) VALUES ('2', '1');

ubb_forum would be your db, ubbt_ would be your table prefix, and '2' would be your user id.

I am a Web Development Contractor, I do not work for UBBCentral. I have provided free User to User Support since the beginning of these support forums.
Do you need Forum Install or Upgrade Services?
Forums: A Gardeners Forum
UBB.threads: UBBWiki, UBB Styles, UBB.Sitemaps
Longtime Supporter & Resident Post-A-Holic
VNC Web Services: Code Modifications, Upgrades, Styling, Coding Services, Disaster Recovery, and more!