file on desktop accidentally got renamed

I have lots of files on my desktop. I just noticed that one of them accidentally got renamed to "k" sometime in the past. I assume it was an accident where I thought I was typing inside an app, but was instead was renaming the file.

How do I go back to the original name? I don't remember what the original name was, and it is important to find out. I could theoretically go back to Time Machine, but is there a faster way than comparing all the current file names with all the old file names? I am always changing them around, so it will take a lot of sleuthing to figure it out that way. It seems like there should be a quicker way.