First off… Don’t think of it as writers block, think of it as writers “fatigue”.

Writers fatigue is a physical thing and it’s simply due to your body and brain being tired or undernourished! So the best thing to do is literally rest and/or feed your body & brain.

Secondly… As noted in a few responses already, you should create an outline for your work upfront prior to starting any serious writing… so just review your outline (or create one if you don’t have one) and flesh out a section that you haven’t touched yet. You can also review a previous section for edits or reflections.

This is what I’ve discovered and these approaches have worked for me.