Hi and welcome
Though there a many very savvy members that frequent this section, you might be best served in the streamer section as there are a few sonos threads in there.
Streamers & Network Music Players | AVForums.com - UK Online.
I don't own a sonos, but do a squeezebox which looks at a nas for music. I know the sonos setup is different, but works on the same principle.
It could be something simple but more info is needed.
How, when it was working great, was it setup before? is the only change the new laptop?
Is everything setup the same on the new laptop as with the previous one with regards to the sonos?
If your music is stored on the laptop, there is no other way for the sonos to access it unless the laptop is on. So where, if not from the laptop, is the sonos supposed to access the music? If music is held elsewhere, its possible that the sonos has lost its mapping to that device. A simple remapping of that device will hopefully get things working as they should.
If you still have the old laptop and its working, you could try reconnecting that and see if everything works as before.
But as said above, more info please