You shouldn't need to reset anything. As per the instructions I linked to, you'll need to connect one of your speakers and then provide the updated wifi credentials.
If you have more than one Sonos product in your system, you'll be asked to connect one of them to your router with an Ethernet cable (which is typically included with each Sonos product). The cable connection is temporary and you may need to move one of your Sonos products closer to the router to do this.
Once Sonos is connected to the router, the Sonos app will ask for your WiFi password. After Sonos has connected to the WiFi network, the app will guide you through disconnecting the Ethernet cable and moving your Sonos product back to where it was before. After one final check, your Sonos system will be back on your home network.
So by 'reset' do you mean that you did a factory reset? If you did that, then you'll need to add them back in as if they are brand new speakers to your system. Did you do this for all of your speakers or just some? If all, then unfortunately, you're going to have to setup like a brand new system.
Danny