I too am getting the output device setting & project sample rate error message. I went ahead and upgrade to Audacity 2.0.6 and reset my preferences hoping it would clear my problem to no avail.
I have no idea what I have done to mess my “settings.” I am running Windows 8/64 BIT. Luis
I started having this loss of sound too…did not even consider it being associated with Audacity. I upgraded to Audacity 2.0.6 and re-set my preferences to no avail. Any assistance is greatly appreciated.
I suggest you work through http://manual.audacityteam.org/o/man/faq_errors.html#sound_device.
If you are still stuck, please tell us exactly what sound device you are trying to play to (make and model number if it is an external device). Are you using that same sound device to play sounds in applications other than Audacity?