Unable to open audio playback device in Cakewalk

“Unable to open audio playback device,”  error occurred when I tried to play an older project (recording)  in Cakewalk ( Bandmix version)

I’m not sure if the old project was recorded using a different interface. I think not. I’m using s Focusrite 6i6 1st generation. After searching the Internet in vain for a solution I came across a fellow who said that he unplugged his interface while in Cakewalk ( with the problematic project opened.) and he solved his problem.

So I tried a variation. I turned the power off on my interface. Cakewalk instantly reacted, asking me if I wanted to forget these connections. I clicked “yes”. Then I tried playback. The recording was advancing in time but without and any audio output. I went into preferences ( edit-Preferences-audio-devices ) and saw that no audio device was chosen, so I selected ASIO.

Pressing playback again, I was able to hear my audio but only via my computer speakers. I went back into preferences, un-selected ASIO and re-selected the Focusrite 6i6. The problem was resolved.  It seems that all my other old projects are playing without any further intervention.