start from ground zero

To begin (something) from the earliest possible starting point; to start (something) at the most basic, fundamental, or preliminary level. A noun or pronoun can be used between "start" and "from." The folder with my outline and notes got deleted, so now I have to start the whole project again from ground zero. We don't have time to start from ground zero, so let's just reuse the assets we made for the last project.