No, Calibre is not abandoned (see the updates) and it works very well for most people.
Try to backup your current configuration.
https://manual.calibre-ebook.com/faq...backup-calibre
Then delete your current configuration and start calibre which will used the Welcome Wizard. Enter your details (e. g. kindle model) and copy / attach your library to calibre.
It would be helpful if you give some details about your configuration - otherwise nobody could help you.