Innodb disabled - MySQL

First check for any disable options for innodb in /etc/my.cnf like
skip-innodb and remove them if there is any. Then restart mysql:

If that doesn't work, try

# /etc/init.d/mysql stop

# mv /var/lib/mysql/ib_logfile0 /var/lib/mysql/ib_logfile0.bak

# mv /var/lib/mysql/ib_logfile1 /var/lib/mysql/ib_logfile1.bak

# /etc/init.d/mysql start

 To check, get into mysql prompt and use the command :

> show engines;

InnoDB is enabled by default. But, MySQL seems to disable it automatically if your InnoDB log files get corrupted. When you remove them, they are recreated, allowing InnoDB to start again.