Sansa 8GB Clip+ erased music but says the space is still there

First, I assume you tried a reset (hold the on button down for 20-30 seconds, or more).

Second, if that doesn’t work and you don’t mind erasing the content you have on the Clip, reformat it under its settings.  (Or, if you can’t do that, reformat it under Windows.)

Hopefully, 1 or the other will do it!