If I can remember correctly, this error shows that the previous mysql session did not terminate correctly and left behind the lock. Mysql is not running in the first place (try ps -ef | grep mysql).
Try stopping mysql (although it is not running, just trying to get rid of the lockfile the nice way) with: /etc/init.d/mysqld stop.
Check the logfiles and check to see if there still is a lockfile. If the lockfile is still there, remove it and try starting mysql again.
Hope this put you on the right track.
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