Getting msg "Cannot play media while alert is active" and no ring tone for calls suddenly

Knew something was wrong when the alarm didn't sound but I hadn't changed anything.  Then later that day realized no sounds for message alerts, texts, etc.  I checked  Sound and Alert Profiles and didn't see anything that would be a problem.  I hadn't changed anything (that I'm aware of anyway) recently so I don't know what's happened that is causing this new problem with my phone.  When I tried to play songs that I had downloaded I get these messages:

"device media processor busy"  "cannot play media while alert is active" and "problem previewing the media".  This is my first smartphone and I haven't had it for very long and have pretty much stuck to just the basics to operate it so far.   So, what I'm saying is I'm not all that tech savvy.  I'm really stumped on this and don't know whether I accidentally changed something that's causing this problem or it's the phone.  For a few minutes today it did seem to be working okay again, but that didn't last long.  Anyone have an idea of what's going on here? And can tell me how to fix it?  Please, I need help with this.

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