MySQL does not start in XAMPP 1.7.3 for Windows - mysql

Question

In 2000 I had installed XAMPP 1.7.3 on my Windows 7 64 Bit machine in F:/xampp. I always started the XAMPP Control Panel Application from this folder, clicked on the "Start" buttons for the MySQL and the Apache so it looked like this:
https://docs.moodle.org/19/de/images_de/e/e6/29_Apache_Stop-de.png
I recently decided to install the XAMPP 5.6.3 version to F:/xampp2. I imported another database and working on this new database was fine.
However, for some reason I cannot start the MySQL server in the F:/xampp any more. The Apache server does start. But when I click on the "Start" button in the XAMPP Control Center the text "Running" flashes up in green for a second (see linked picture above) and vanishes again. Nothing happens. In (this version 2.5.8 of) the Control Panel no additonal info is displayed in the log.
I tried everything to avoid a duplicate posting:
The other Mysql server in F:/xampp2 not running. The Port Check function of the Control Panel says 3306 is free.
Skype is not running.
There is no mysqld.exe in the Windows Task Manager
Checked services.msc - there is nothing running related to MySQL.
I ran netstat in a command line and there was no sign of 3306 anywhere.
I changed 3306 to 3307 in the f:/xampp/mysql/bin/my.ini. Nothing!
There are many threads like this one and I tried everything except to "delete and reinstall". I cannot delete F:/xampp - I have 500 GB and 500 tables of data in the F:/xampp MySQL database that my life depends on. I do not even want to touch the data in there and risk any loss. I cannot delete F:/xampp2 either. What can I do?
Thanks!
EDIT: I tried the following in the commandline:
f:\xampp\mysql\bin\mysqld.exe
150602 6:03:24 [Warning] Can't create test file \usr\local\mysql\data\MY-PC.lower-test
150602 6:03:24 [Warning] Can't create test file \usr\local\mysql\data\MY-PC.lower-test
f:\xampp\mysql\bin\mysqld.exe: Can't change dir to '\usr\local\\mysql\data\' (Errcode: 2)
150602 6:03:24 [ERROR] Aborting
150602 6:03:24 [Note] f:\xampp\mysql\bin\mysqld.exe: Shutdown complete
EDIT 2: I looked for the mysql.err file in f:\xampp\mysql\data.
150602 7:04:01 [Note] Plugin 'FEDERATED' is disabled.
InnoDB: Error: log file \xampp\mysql\data\ib_logfile0 is of different size 0 5242880 bytes
InnoDB: than specified in the .cnf file 0 1073741824 bytes!
150602 7:04:01 [ERROR] Plugin 'InnoDB' init function returned error.
150602 7:04:01 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
150602 7:04:01 [ERROR] F:\xampp\mysql\bin\mysqld.exe: unknown variable 'innodb_file_format=barracuda'
150602 7:04:01 [ERROR] Aborting
150602 7:04:01 [Note] F:\xampp\mysql\bin\mysqld.exe: Shutdown complete
EDIT 3: Thanks for your comment, I tried the following but it there are other errors:
f:\xampp\mysql\bin\mysql --help
gives me inter alia:
Default options are read from the following files in the given order:
C:\Windows\my.ini C:\Windows\my.cnf C:\my.ini C:\my.cnf f:\xampp\mysql\my.ini f:\xampp\mysql\my.cnf
then i try this line and I know that the my.ini file is there:
f:\xampp\mysql\bin\mysqld.exe --defaults-extra-file=F:\xampp\mysql\bin\my.ini
150602 14:39:21 [ERROR] Can't find messagefile '\xampp\mysql\share\english\errmsg.sys'
150602 14:39:21 [Warning] Can't create test file \xampp\mysql\data\MY-PC.lower-test
150602 14:39:21 [Warning] Can't create test file \xampp\mysql\data\MY-PC.lower-test
f:\xampp\mysql\bin\mysqld.exe: Can't change dir to '\xampp\mysql\data\' (Errcode: 2)
150602 14:39:21 [ERROR] Aborting

Answer 1

Open a command prompt - press Win key + R and type in cmd.
In the command prompt type in F:\xampp\mysql\bin\mysqld.exe and press Enter. (note it is mysqld with a d in the end)
What do you see? There should be an error, possibly regarding your config file.
EDIT:
Try using:
F:\xampp\mysql\bin\mysqld.exe --defaults-extra-file=F:\path\to\config