MySQL installation error: can't start MySQL service due to InnoDB engine failed
If the MySQL service doesn't start, you need to verify the Event Viewer for error logs.
In the particular case of seeing the error Plugin 'InnoDB' registration as STORAGE ENGINE failed
1. Navigate to the datafiles of MySQL, typically located here: c:\programdata\mysql\mysql server 5.5\data
2. Make a backup and delete the files that istart with ib_...(ib_logfile0, ib_logfile1 and ibdata1)
3. Restart the MySQL service on Services (usually located in Control Panel > Administrative Tools)