Hi @bal12345 ,
Some Courses have this, but this one hasn’t, but:
It is a good habit to make incremental Saves, each Lesson, or when you enter a new stage in your project.
This can be done really easily in Blender, if you Save As (SHIFT+CTRL+S) and then press the + sign:

Also, you might find a recent version of your file in one of your questions here, so you don’t have to start from scratch…
…and, unintuitively, it is not a bad thing, to start from scratch sometimes (especially in the beginning of your Blender journey): it’ll be a lot faster than the first time, and you’ll be more aware of (some of) the pitfalls to avoid.