Discuz! Database Error 怎么解决

1 上午还好好的，下午就用不了了 ，中间未登陆管理后台

Discuz! Database Error

(2002) notconnect
PHP Debug

No. File Line Code
1 portal.php 18 discuz_application->init()
2 source/class/discuz/discuz_application.php 65 discuz_application->_init_db()
3 source/class/discuz/discuz_application.php 399 discuz_database::init(%s, Array)
4 source/class/discuz/discuz_database.php 23 db_driver_mysql->connect()
5 source/class/db/db_driver_mysql.php 75 db_driver_mysql->_dbconnect(%s, %s, %s, %s, %s, %s)
6 source/class/db/db_driver_mysql.php 88 db_driver_mysql->halt(%s, %d)
7 source/class/db/db_driver_mysql.php 224 break()

求大神指点