Hi @Beabeabea1
Welcome to the Sonos Community!
Sorry to hear of this issue you are having with many of your speakers being missing from the Sonos app.
Looking at your account, I can see that there is a separate system of two speakers that I think you are connecting to, and, as a result, are unable to see the speakers that are configured as a different system. You can confirm this by unplugging those speakers from power and restarting the app - you will then connect to the larger system. To remedy this, you will need to factory reset those two speakers and add them to your current system, rather than to set them up as a new system. Always ensure that the app is connected to your system before setting up any new or reset speakers. The app will usually prompt you to add found speakers anyway.
As for some other speakers, they appear to be offline. This means they are either powered off, on but not connected to WiFi, or on, connected to WiFi but cannot reach the internet. If you are unable to easily resolve this, I recommend you get in touch with our technical support team who have tools at their disposal that will allow them to give you advice specific to your Sonos system and what it reports.
I hope this helps.