Adrianne replied
Hello,
I just came back as I realised why this happened, so I wanted to let everyone else know who might read the ticket, so it will save them time too if they do this.
So this was sort of my fault as I watched the video, did the install to update theme via the plugin (which I have since deactivated), but then I activated the parent theme, however I have been using the child theme.
So my issue was that the parent theme didn't have the custom css changes/codes I had in there!!
I looked at this further this morning and was able to activate the child theme and all of the css came back.
Hope that solves a problem for someone else at some point too.
Thanks Penci!!
Adrianne