How to rehang vertical blinds on a damaged bay ceiling?
The brackets have pulled out because they were not properly attached to a structural member. The best fix in this situation would be to take the blinds down, and reinstall them properly by attaching them to studs/joists.

While most blinds come with those small "anchors", these are almost never sufficient to support the blinds.  The best way to install any type of blinds is to locate structural members inside the wall/ceiling, and use longer screws (usually not included) to attach the brackets to these members.  

If it's just not possible to attach the brackets to structure, the next best option is to use toggle bolts. Toggle bolts will give you greater support, and will be less likely to pull out.  These driller toggles from COBRA are a great combination of screw-in drywall anchors and toggle bolts.  They provide a good hold, while still being very simple to install.

To rehang the blinds you should be able to use the same holes, if you're using a toggle bolt that is about the same size as the existing holes.  If you are moving the brackets to a new location (to attach to a framing member), you can patch the existing holes with joint compound.