You would generally need to 'mount' a filesystem to view the contents. To modify the partitions, you would unmount them. If you can still boot Mint, open a terminal and run this command to get drive/partition information: sudo fdisk -l(Lower case Letter L in the command). If you look at the output of the command, the far right column - System - should show the type of filesystem. If you have one or more showing " HPFS/NTFS" then you still have windows partitions. You could mount the partitions to see if your data is still there if the partitions are not mounted.
I was able to run some command I googled to unmount windows and view the partitions