@freckles1971, I just went through this. I looked in my folders and found a second, empty, mods folder.
What I had to do was move the folder with my mods to the desktop then move all of my mods to the newly generated mods folder. Then I deleted the cache files that are deleteable and restarted my game.
The mods were all there and the popup returned but I ran into another problem: My saves disappeared.
Of course, where did I find them? In my mods folder amongst the mods.
So if you try this, take a breath, relax, and go slowly so you don't, unintentionally, move the wrong thing into your mods folder like I did.
