When you happen this problem,according to your system environment,so ,may be have some solution:

1,the first:

*cat /var/log/mysql.log

*service mysqld stop

*ps aux | grep mysql

*kill -9 ??? / killall -9 mysqld

• rm -rf /var/lib/mysql/*

*service mysqld start

Finish above these may be is ok,may be is not.

so ,and look at the following:

2.