Sage 7.3 jupyter notebook not showing on VM

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I have just installed Sage 7.3 withinthe Oracle VM. I am completely new with sage and a bit rusty on general IT skills!

At the beginning I was able to see the Jupyter notebook on the virtual machine itself (without needing to open the local host web page). After playing around a bit I now get a blank screen with the following command line prompt

[sage@sagevm ~]$_

I can still see the Jupyter notebook on the local host (Is this sufficient?) but I was wondering how I can get back to opening the notebook on the VM itself. I have tried using Right Ctrl F2 or typing notebook() but this does not seem to help. Not sure whether I'm in the right directory or what else I should try. I'd appreciate any help with the above Many thanks! George