If it’s working on XP, I assume you have files on it that you want to keep?
This may help you see it if it‘s hidden, right-click Computer > Manage > Storage > Disk Management then right click on the drive that is 'hidden' > Change Drive Letter/Paths... > select a letter from the end of the alphabet > OK and the disk should show in Computer. Try another letter if it stays hidden.
If you really want to format it, right-click Computer > Manage > Storage > Disk Management. If the drive is completely new, a message “You must initialize the disk…” appears, click OK. Now right-click the graphic for the drive then choose “New simple volume”. Allocate the amount of space you want to use, i.e. all of it or some of it so that you can have more than one partition on the disk. Now format it. Repeat the “New simple volume” procedure if you have decided to make multiple partitions. If I remember correctly the new drives are then labelled “Healthy, Primary” in the graphical display.