Thanks for the help, and sorry for unfilled subject.
I tried to return the name of "admin" in this way. But access is not came back.
mysql> update groups set name='admin' where id=2;
Query OK, 1 row affected (0.09 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> SELECT * FROM groups ;
+----+-------------------+------------------------------+----------+---------------------+-----------+---------------------+-----------+
| id | name | comments | valid_id | create_time | create_by | change_time | change_by |
+----+-------------------+------------------------------+----------+---------------------+-----------+---------------------+-----------+
| 1 | users | Group for default access. | 1 | 2015-02-19 08:06:39 | 1 | 2015-02-19 08:06:39 | 1 |
| 2 | admin | Group of all administrators. | 1 | 2015-02-19 08:06:39 | 1 | 2015-03-04 12:17:20 | 2 |
| 3 | stats | Group for statistics access. | 1 | 2015-02-19 08:06:39 | 1 | 2015-02-19 08:06:39 | 1 |
+----+-------------------+------------------------------+----------+---------------------+-----------+---------------------+-----------+
4 rows in set (0.00 sec)