I frequently use a Linux Mint USB drive to boot up failed Windows PCs.
I always need to look at the hard disk to see if it is good and if files can be read from it.
But very often the disk cannot be mounted because it has been marked as in use by Windows.
But it can be mounted "Read Only" like this:
Open the Linux terminal and type:
sudo mkdir /media/anyname
sudo mount -o ro /dev/sda1 /media/anyname
and it will then be mounted.
(Obviously replace sda1 in the above with the appropriate disk, and you can replace "anyname" with any name!).