@Martynk1966
To create a new Sonos system you need several things… a Sonos Speaker that has been reset to factory settings.. that can be done easily if you follow the steps in this link:

https://support.sonos.com/s/article/1096

WARNING: Resetting your Sonos speakers will erase all previous settings, services and playlists etc.

You also need a mobile ‘controller’ device that meets the requirements in this link:

https://support.sonos.com/s/article/4875

You need a local WiFi network that meets these requirements:

https://support.sonos.com/s/article/126

And a new/reset S2 Sonos App. Here’s a link showing how to reset the existing App:

https://support.sonos.com/s/article/4758

STEPS…

Just reset the speaker and you will see it’s status light will flash green showing it is ready for setup. Open the new/reset Sonos App on a compatible mobile device connected to the local WiFi network and follow the onscreen instructions to create a new system and add the Factory Reset speaker(s) to the App.

Then add your music services etc. 

Great answer by @Ken_Griffiths ! However, I’m curious to know what you mean when you say “SOMEHOW” your account has been taken over by your daughter. The only legitimate way for that to occur is through a “transfer of ownership” via the Sonos App. On the other hand was your statement just a figure of speech?