How do I open a project that is missing an add-on?

I have a project that was just created last month.

And I have the drop shadow add-on from

construct.net/en/make-games/addons/92/drop-shadow

I cannot open the project now as it says it's missing the add-on

The plugin has become [???] in the list, is there are way I can create a dummy plugin and remove it after I open the project?

You don't need to zip the files back, you should be able to open .caproj file in Construct 3.

And after you open the project, save it as a new c3p file.

.

By the way, you may need to remove references to this plugin from other files, in ObjectTypes and EventSheets folders.