Do you have the Advanced? If yes, open first the script debugger and only then open that file.
Thank you so much! I appreciate the response.
For or the edification of any others facing this issue, it appears my situation was far less dire.
Apparently FileMaker as an application was not responding properly anyhow. After restarting my computer, the application and file opened fine.
Again, thank you so much. I will very likely be using the script debugger fairly soon as well.