You normally have to do this when you are dual booting and your windows partition is in a state of hibernation.. Linux sees this and refuses to touch files
Complicated Linux Suggested Method:
sudo mount -t "ntfs" -ro "uhelper=udisks2,nodev,nosuid,uid=1000,gid=1000,dmask=0077,fmask=0177" "/dev/sda2" "~/Desktop/D/"
Where ‘D’ is a folder you previously created to mount the drive (mkdir ~/Desktop/D)
If for some reason this doesnt work.. you can force delete the hibernation data by
mount -t ntfs-3g -o remove_hiberfile /dev/sda2 ~/Desktop/myplacetomount