You cannot convert a FileMaker file into an Excel file in the way that you describe. You can, however use either Export Records or Save/Send Records as Excel to create a copy of your data in a new file that is an excel file.
But these options leave your original FileMaker file unchanged.
Oh it's possible because it renamed my file to "Filemaker Pro Converted". I looked through the forum and it looks like I'm more than likely the first person to do it. But through this disaster I created a new database from scratch that looks 10 times better than the original. Still would like to get the original back up and running to get those files back.
Sorry, but it absolutely is not possible.
Renaming a file does not convert it. It just changes the name of the file. Even changing the file extension does not actually change the file--it only changes the icon supplied by your operating system to identify what program will launch when you double click that file. All you should need to do is change the name of the file back to the original name if this is what you actually did.