Mp3 not showing in library

I spent an hour trying to get this to work so I could get some sleep in my noisy hospital bed last night. I wanted to listen to some noise on loop. I downloaded some waves lapping type music. It's on my internal SD and is an mp3. Clicking the file in Astro browser doesn't open the file in a player fully but only a popup preview window. It's in the foreground, doesn't offer many controls and stops playing when the focus is removed. Searching for the file in all 3 of my players doesn't result in anything, even after a restart. I have also tried a SD card rescan utility from the play store. Music apps I tried were Fusion, Bubble UPNP and the Samsung Music App. All of which seem to rely on some internal media index. Frustratingly I can't simply browse to the file from inside the apps, I have to search the library. It should not take an hour and a post to here to figure out how to manually play a simple file, added to my phone in such a way. It would be great if it were like Windows or osx and allow the user to "Open with... ", and then select the app. I know you can dig in and change this, but it's a more permanent solution for a temporary requirement. Anyway I must be loosing my mind:) How can I add this file to my library from within Android or otherwise open this file in a full player to make use of controls like loop etc? ---- Update from a comment on an answer: It's mp3, and plays in the popup player just fine. Perhaps the tags are corrupted and somehow blocking it from appearing in the library. I tried an mp3 tag utility and it can't see the file in the folder. So perhaps it is corrupt in some way.