Ok so I finally bought a backup external storage and yes, this could have prevented my problem and yes, this will be a painful lesson. I have a 1tb (or maybe 2) 2011 iMac and it did a high Sierra update overnight but failed. I couldn’t get disk utilities to reinstall and I was left with purchasing an external drive, formatting and installing a fresh copy of HS. Only now when I was in HS (on my external) my internal drive looks like it’s empty. It’s only showing a 1TB capacity with all space available. I tried a free recovery program just to see what it would find and it started to find thousands of images from my camera so I know they’re there somewhere. However I have a lot of videos and images I need to recover. Can anyone recommend a good recovery solution? I have no idea what is going on. Thank you!!