Lost vintage harmonica with brown leather case left on a bench in Liberty Park near 39th Street and Broadway Ave.

I lost my favorite vintage harmonica along with its brown leather case while walking in Liberty Park, near 39th Street and Broadway Ave in Northwest OK. I set it down on a bench for a moment while I tied my shoes, and when I returned, it was gone. It has great sentimental value as it was a gift from my grandfather, and I'd appreciate any help in its recovery.