[jpindar]

What are you trying? Do you want to read things with Calibre's built in reader, another desktop reader, sync them to a device (i.e. use the desktop GUI to copy files to a device), download them to a device via the content server or what?

[g051051]

I don't care how I read my stuff, I just want to read it. Calibre says it supports lots of formats, but somehow I can't find or figure out the magic inputs or config options to have it display something to me so I can read it.

[jpindar]

OK, first make sure the books are really there. Right click on a book entry, and click "open containing folder". Make sure the book file is there and isn't corrupted.

If it's OK, you should be able to read any non-DRM'd file of most formats by right click > View > "View with calibre e-book viewer".

You can also try any other ebook reader by clicking the "Configure Calibre" icon to open the Preferences dialog. Under "Behavior" find "Use internal viewer for" and uncheck the file format. Then when you right-click > View > View, Calibre will use your OS default viewer for that file format.

If you have DRM'd files (such as from Amazon), you will need a plugin to remove the DRM. The best way to find these is to look on https://www.mobileread.com which is a good place for Calibre discussion in general. I used to know how to do the Amazon ones but it's been a while, there might be a new way by now.