I saw the following just now from a year ago, and then a message that it was fixed. I am now experiencing the EXACT same problem, in Jan 2018:
"I have had this problem for 2 days now, Spotify will not play anything on my laptop, it keeps saying "track not available". I've tried uninstalling the app and reinstalling it, I've checked my firewall settings so that is not blocking anything, I've tried to change the playback device, I've tried turning it off and back on again, nothing works. On my phone it plays just fine. Never had this problem until I became a Premium user a few days ago. I don't know what to do anymore"
We’ve received news that this should be fixed on most of the devices that were previously reported here.
If, unfortunately, you still experience playback errors on Windows, then this could occur for a number of reasons.
We’ve worked hard to ensure that Spotify will work with a lot of different hardware playback setups. If you’re still unable to play some music on Spotify in Windows, let us know in a new report and we’ll work with you to resolve the issue.