Hi @nbelani, welcome back to the Community.
This sounds like the Sonos S1 app is looking for the S2 system and generally happens after upgrading to S2.
You’ll need to reset the Sonos S1 app to reconnect to the Play:5 Gen 1. Depending on the status of the Play:5, this will change how you reconnect.
If the Play:5 is Factory Reset, the LED is flashing green when plugged into power, then you’ll need to set up a new system. If the Play:5 has a solid white LED when plugged into power, then you just need to reset the Sonos S1 app and connect to an existing system.
I hope this helps you reconnect to your Play:5 to get it up and running again!