@Ghastlyghost You may need to buy another external drive ( you would probably need to add space soon anyway). But when you get this drive format for the windows machine and make sure windows can read the drive. Then you get another machine that can read your old drive and can read the new drive formatted for the windows 10 set up. Copy your data across to the drive windows says can read. The move the disk back to the windows machine and see if it can read it. Long way around, and assuming you have more than one machine