Comment 1 for bug 1637280

Same problem here. To make MySQL start again, I had to manually type the following commands:

sudo mkdir /var/lib/mysql-files
sudo chown -R mysql:mysql /var/lib/mysql-files/
sudo chmod 700 /var/lib/mysql-files/

For some reason, updating does not trigger that code in mysql-server-5.5-postinst.

I also tried:
sudo dpkg-reconfigure mysql-server-core-5.5
and
sudo aptitude reinstall mysql-sever-core-5.5

with no success.

This was not that easy to find out, because when "sudo service mysql start" is run, no output at all is produced in either of these files:
/var/log/mysql.err
/var/log/mysql.log
/var/log/mysql/error.log
Just the following is printed in /var/log/syslog:

kernel: [ 5613.296491] init: mysql main process (14542) terminated with status 1
kernel: [ 5613.296500] init: mysql main process ended, respawning
kernel: [ 5613.302257] init: mysql post-start process (14543) terminated with status 1
kernel: [ 5613.315931] init: mysql main process (14569) terminated with status 1
kernel: [ 5613.315940] init: mysql main process ended, respawning
kernel: [ 5613.317918] init: mysql post-start process (14570) terminated with status 1
kernel: [ 5613.331260] init: mysql main process (14596) terminated with status 1
kernel: [ 5613.331268] init: mysql respawning too fast, stopped

And to find the actual cause I had to type: sudo mysqld start