Cubase LE AI Elements 8 with Windows 10 playback

This is my very first forum ever for anything so please excuse any mistakes in forum etiquette…!

I have been using Cubase for years to record my piano students for take home CD’s. Recently I bought a Zoom H4n recorder for more portability and with it came an upgrade in software to my old Cubase AI. Also, I swapped out my old laptop and Vista for a new"er" laptop running Windows 10.
After struggling with the e- licencer and installing Cubase on the new computer and learning my way around the software everything was working well.
About 2 weeks however, all of a sudden when I went to playback a recording that I made using Cubase, it would only playback through the laptop speakers! I tried turning everything on and off, I tried plugging Cubase in to each different port on the laptop, I’ve checked the output in VST and on the computer - there seems to be nothing wrong. AND!!! Playing anything else - like youtube with Cubase plugged in - it DOES play through my external speakers.
It’s only playback from Cubase that won’t playback through Cubase.
Can anyone please help me?