Can't Open Production Anymore

Premiere Pro doesn't set up an OS-level link to the .prodset file, meaning double clicking a .prodset file doest not open Premiere Pro. To open your production you can either:

1. Open one of the component project files
2. Go to File > Open > Production and point it at the top level of the production folder

That looks like your OS lost it's link to PP for prodset files. Reinstalling PP might help. As Neil asked, can you open it from inside PP. We have utilities in Windows for fixing things like that.

How about launching Premiere from your desktop, and opening the Production from Premiere's menu?