# Mount an ext4 partition /dev/sda1 to folder /media/omg
sudo mount -t ext4 -v /dev/sda1 /media/omg
# Then unmount it
sudo umount /media/omg
# In case you don't remember exactly your partition is
# /dev/sda1 or /dev/sda2 or /dev/sda3 or ...
# you can use this command to figure it out:
sudo blkid