Audio Playback Not Working
S2 - Critical
1) Haven't opened MuseScore in about two weeks or so / It would update when necessary
2) Audio playback is not working for any previously made scores / projects
See https://musescore.org/en/node/96811, and if that doesn't help, please ask for help in the Support forum and provide more information )eg, your OS, specific version of MuseScore as per Help / About, and what settings you see in Edit / Preferences / I/O after doing the revert to factory settings as suggested).