Unable to start mysql on ubuntu
Trying mysql's built in table check/fix/ etc functions did not help my in restarting mysql server in regular mode.

I ended up:
1) doing mysqldump of all the databases, into one file.
This article was immensely helpful

2) dropping 1 db at a time, and attempting to restart mysql server in regular mode, after each drop (nothing helped).

3) I ended up purging mysql from ubuntu all together, and re-installing it.  

4) I did the sql dump restore doing the following command (took 3 hours for 200gb dump, on a fairly fast machine):  

mysql -u root -p  &lt;  /home/zzzzz/all_databases.sql


Best of luck, and hope this doesn't happen to you - it was definitely a waste of 2 days of trial and error, with the nuclear option as my last restort.