No. Don’t reinstall postfix. That won’t do anything useful. You have a configuration problem, nothing wrong with Postfix, it’s doing exactly what you tell it. Reinstalling things should not be your go-to solution, especially without understanding what’s gone wrong. You’re likely to just repeat the same mistakes.
You can disable mail for the domain and then re-enable it, and as long as configuration is right, the virtual map should do the right thing, I think. (Though it might require disabling/re-enabling mail for the users, instead. I don’t remember under what circumstances virtual map entries get removed.)