Playback

I used to be able to simply “drop” an MP3 into Audacity, edit it & playback snips. However, for some reason when I attempt to “drop” an MP3 or playback a snip now, I get the following message:
“Error opening sound device. Try changing the audio host, playback device & the project sample rate.”

  1. I did NOT change anything beforehand.
  2. What is this referring to & how do I fix?

Is this issue specific to dropping MP3s into Audacity, or does the same issue occur with all audio in Audacity, irrespective of how the audio gets into Audacity?