Unable to find the .lit file reader app clit

Download Calibre - this will read your LIT format files, and also be able to convert them to other formats.

OR

you can install the clit program by sudo apt-get install convlit

The general solution to the question “Which package provides file X?” is to use the in-packages search feature of the official site's Ubuntu Packages Search page.

Scroll down to Search the contents of packages (the second search form on the page — using the first is an easy mistake and will give frustrating results).

Enter your desired filename in the search field and hit Search, and there it is: