I hvae been working on a file the past few days. Fairly simple stuff like adding pictures and text. But when I jumped onto my computer this orning and tried to open the file, I could an error message saying it could not be opened. The error message states that it could be an unsupported file format, plug-in that's not supported, or that the file may be open on another computer. I also now notice that the file is .indd.icloud, but I have no memory of making it an icloud file.
Sorry to hear about your experience. I hope your issue is resolved by now. If earlier responses helped, we'd appreciate if you can mark the relevant response correct. If you used any other method, you may share it with us. It'll help other users with the similar concern as yours.
If you still have issues, you may share a sample file with us. We'll be happy to take a look.