MySQL crashed and not picked up, what should I do?

Question

linux

After restarting the server, mysql does not rise, the restart gives an error:

InnoDB: Error: log file ./ib_logfile0 is of different size 0 67108864 bytes
InnoDB: than specified in the .cnf file 0 50331648 bytes!
InnoDB: Possible causes for this error:
 (a) Incorrect log file is used or log file size is changed
 (b) In case default size is used this log file is from 10.0
 (c) Log file is corrupted or there was not enough disk space
 In case (b) you need to set innodb_log_file_size = 48M
[ERROR] Plugin 'InnoDB' init function returned error.
[ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
[Note] Plugin 'FEEDBACK' is disabled.
[ERROR] Unknown/unsupported storage engine: InnoDB
[ERROR] Aborting

Answer 1

First, you can check the disk.
is there free disk space?
what are the mount options?
Then try restoring from a backup.
remember if you updated mysql? do not upgrade the DBMS without backups!