I'm not sure what ID # in the XML file you say that you changed. The Image ID that I can see in your earlier screenshot is an ID that Reflect auto-generates every time you create a Full, not something you manually specify in the XML file.
An XML file is basically just a saved list of settings that describe a backup job, such as what to back up, where to send it, what retention policy to apply, whether to use encryption, compression, email notifications, etc. It just makes it faster to create NEW backups since you don't have to step through a wizard to specify all of those settings every time. But you HAVE a backup, you can restore it by going to the Existing Backups tab, selecting the desired backup, and clicking Restore (or Browse if you just want to extract content). The backup files contains everything needed to perform a restore. The XML file is not part of the restore process.
But as a general tip, this might be a good example of why it can be good to post screenshots. Your question about how to restore from an MRIMG file without an XML file suggests that you might not be performing the correct steps to accomplish your goal. Sometimes that becomes clear when you post a screenshot, because it provides much more insight into where you are in the application or what you're doing than just writing "I get an error when I open an MRIMG file." And it's still not clear from your post whether you're using Reflect in full Windows or the Rescue Media environment, whether you've tried both environments, and if you're in full Windows exactly what you're doing to try to open an MRIMG file. Are you just double-clicking them in Windows Explorer, or are you trying to use them from within Reflect?
Another option you might want to consider would be checking the Reflect Online User Guide. You can access it from within Reflect by going to the Help menu and clicking Help, or
here is a direct link. It contains a lot of helpful information, including how to perform a restore from an MRIMG file.