1. To start something completely new, without any prior progress or preparation; to start over from the beginning
After the computer crashed, I had to begin from scratch on my project.
Depois que o computador travou, tive que começar do zero no meu projeto.
2. To initiate an activity without using any existing materials, tools, or previous work
Since there were no recipes available, the chef had to begin from scratch.
Como não havia receitas disponíveis, o chef teve que começar do zero.