How to repair plesk if you can’t access it or something is broken?

Repair a broken Plesk / Odin installation from SSH commandline with these commands:

Repair all Plesk components:
plesk repair all
Repair all Plesk components and answer all questions with Yes:
plesk repair all -y
Don’t actually repair but report broken components:
plesk repair all -n

Instead of all you can use specific components like: mail, web, dns, ftp, file system, plesk database, mysql, installation and all the subcategories of the components

For more information refer these pages:
https://docs.plesk.com/en-US/12.5/administrator-guide/plesk-administration/plesk-repair-utility/plesk-repair-utility-all.74650/
https://docs.plesk.com/en-US/12.5/administrator-guide/plesk-administration/plesk-repair-utility.74649/