[villagetinker]

OP, I would go into the attic with a flashlight and see if the tube is torn or disconnected on the attic. You can also have a person shine a flashlight (a night) into the solar tube from inside the house and see if you see any light in the attic. If you do, this is a bigger problem, and you will need to contact a solar tube installer for the repair. If you do not see any light or tears, then I would remove the lens inside the house, and apply some sealant to the ring and push back into place, and after the sealant has dried, reinstall the lens. If you cannot do this, a handyman should be able to help.

I am only working from the picture, but it does appear that some screws might be missing as the only other solar tube I looked at has screws to a mounting ring inside the attic.