What will you do if there is no documentation and you have to create it from scratch?

If there is no documentation and it needs to be created from scratch, I would:

1. Gather all available information: interviews with developers, analysts, users.
2. Define the target audience of the documentation and its format (technical, user, API, etc.).
3. Structure the information by sections and priorities.
4. Create a draft version of the documentation, including diagrams, process descriptions, and examples.
5. Conduct a review with stakeholders for clarification and additions.
6. Provide support and update the documentation as the project develops.

This approach will help make the documentation clear, useful, and up-to-date.