When I open my project all shadows have gone I am using blender 2.9 am creating a room with chocofur model manager for furniture, etc, it looked nice with all the shadows and lighting but I have saved it every step of the way, but now when I open it all shadows have gone and nothing happens when I try to add the process again. I have watched tutorial again and again and everything is right.
I don't have enough reputation to comment, sorry.
In addition to Christopher Bennet's comment (making sure you are in the rendered viewport, Z -&gt; Rendered) I will suggest another possible cause for future readers.
In Eevee, one can turn off shadows manually for each light source. You can click on a light source in the outliner, go to object data properties (the light bulb). There you can select two checkboxes: Shadow and Contact shadows. Check if these have not been accidentally turned off.