Puppet suddenly turned into test screen

Bill is right. Click on the puppet name in the Project panel and then in the Properties panel, you will see the link to the puppet highlighted in blue. Sometimes clicking on the link is all you need to do, but if necessary, redirect the path to the proper location of the puppet.

You may have moved your artwork or renamed it. CH can find your original if you click on the puppet in the project panel, it will then light up in blue on the right under puppet. That should locate your original.