Hi Modeste Muhire,
Thank you for contacting us through the Microsoft Q&A forum.
Microsoft Learn does not provide direct access to previous sandbox environments within a training module. These sandboxes are typically ephemeral, meaning they are temporary environments that do not retain data between sessions.
We recommend initiating a new sandbox session in the 'Exercise - Try out Git' and completing the module 'Introduction to Git' first. We suggest revisiting the exercise steps you previously completed, which may require less time since you already possess the knowledge from your initial attempt. Ensure that you finish the next module within the same activation window of the sandbox.
Microsoft Learn sandboxes are temporary environments intended for practicing concepts and have a limited lifespan of 1, 2, or 4 hours, depending on the module. They automatically deactivate after a period of inactivity and require reactivation upon expiration.
Please note that you are allowed 20 sandboxes per day, with additional sandboxes available the following day.
If you continue to face issues, please let us know in the comments. We are happy to assist you further.
If the information is helpful, please consider clicking the "Upvote" and "Accept Answer" on the post.