I’m impressed that it worked until 4 months ago.
 

The Play:1 has no microphone, so to the best of my knowledge it cannot, and has never, worked with voice control (unless you had a Dot or similar to control it). 

Hi @Hannah1010 

Welcome to the Sonos Community!

Assuming that you do have an Echo or similar (@nik9669a is correct), there’s likely an issue with the security tokens that the two devices exchange with the servers involved (Alexa, Sonos and Spotify). To resolve this, I recommend you get in touch with our technical support team, who will guide you through the process of decoupling the Sonos device from the services so that connections can be re-established. I recommend a call in the first instance.

Please do not factory reset your Sonos devices without being instructed to do so - it rarely helps, and there is an inherent risk in doing so. Not to mention all the extra work it creates for you.

You could also go through my post here: Tips & Tricks - Resolving Most Alexa Issues | Sonos Community

Apologies, it's the sonos1.  

Perhaps you mean the Sonos One? There is no Sonos1….

And yes, Sonos’ naming conventions are, shall we say, a tad confusing….

Well, some steadfast and courageous souls managed to cope somehow without voice control for the first fourteen years that Sonos existed. Rumour has it that there are primitive tribes in the Amazonian rainforest who still use the app. :)