I've just created a new thread for you. Next time please don't add your question to an existing thread (even if it's similar) - create your own one.
Look into your /etc/fstab file. You should have a line like this
/dev/hda4 /windows/D vfat defaults 0 0
If it doesn't exist, create it. Then check if there's /windows/D. If not, create it:
Then you should be able to mount it:
mount -t vfat /dev/hda4 /windows/D
After a reboot it should be mounted automatically.