I just watched this question get closed as off-topic. The question involves reinstalling / recovering accidentally deleted packages in Ubuntu.
Granted, it is an older version (16.04), but I was under the impression that all Ubuntu versions were within the scope of Ask Ubuntu. Am I wrong about that or overlooking another detail?
I can see it needs improving. OP left out a few major details, such as which packages are missing. I am sure that it has duplicates under different contexts, but as you know, with Linux systems, what works in one instance may or may not work in the next.
Regardless, I don't understand how it is off-topic.