Why are you resetting the speaker?

Did you follow the steps in this article exactly?

https://support.sonos.com/en-us/article/reset-your-sonos-product

Thank you very much, I tried several times but it doesn't work for my device. The green light just doesn't appear and I can't complete the reset.

Get the numbers off the bottoms of the speakers and call Sonos support, maybe they can help.

Are you pressing and holding the Play/Pause button until the light flashes white and orange? And once the light flashes white and orange, are you letting go of the Play/Pause button?

Why are you resetting the speaker?

Exactly. I want to do a factory reset to connect it as new, like a newly bought device. Because it does not work correctly. But I can't do it. The green light just doesn't appear.

If you purchased the speaker used, it may be defective. I would contact Sonos Support and have them check it for you.

I have same issue. One of my Play:1s wasn’t connecting. After basic troubleshooting, I decided to reset (something I’ve done in the past successfully over the years). But it never turns green. It will even show up as a device to add but no tone is heard and when press button as plan B if tone sound doesn’t work, that doesn’t work either. 
 

In had the same problem with a Play:1. After several resets, I tried connecting it with an Ethernet cable to the router and performed the reset again. After a couple of minutes, the green led appeared and I could add it again to my system.

Tomva has the answer that worked for me. I was only getting an Orange blinking light, never Green. And while it would go through the setup process, it would never play the chime sound (Audio pin).
After connecting an ethernet cable it worked for me like this:

1. Connect an ethernet cable to your Sonos Play 1, and to your internet enabled router or switch
2. Plug in power while holding Play/Pause
3. Wait for the light to blink Orange.
4. Release the button and wait a few minutes. It will blink White for a bit and then will turn Green.

Once you have a green light it should connect properly when setting up, and play the chime audio pin.