Yikes! Most likely it's there. Anaplan would never delete your model. Try sorting the models in your workspace by clicking on the model column. Then scroll down to your model. See if that helps. If not, make sure your pointing to the right workspace. To do that click on your profile, then right below the "my account" is a place where you can change the tenant. Hover over that, and you should see the word "change" appear. Click on that and select the right one.
Hope that helps. If not, let's keep trying. I guarantee your model is there.