How Can I Get My Onscreen Keyboard to Appear Again in Snap Scene?

It's possible the system keyboard got disabled by mistake.  The System Keyboard is an onscreen keyboard that opens when a text field is selected. Enable the System Keyboard when you don’t have a physical keyboard for your device. The System Keyboard is enabled by default.

The System Keyboard is only available on the Windows platform.

Enable System Keyboard
1. Select Show Tools.
2. Select Settings.
3. Select System Options.
4. Check the System Keyboard box.
To disable the System Keyboard, simply uncheck the box in the System Options section of the Settings menu. If you
are using a physical keyboard, it is best to disable the System Keyboard.