Debian Installation :: How To Access Unmounted Partitions In Jessie

I have recently installed debian jessie on my laptop , during installation i didn't mount 2 of my partitions , now when i want to access them i have to give the root password every time i click on them , i searched the google , i found that i have to add a line in fstab file : so i i checked the partition that i wanted to mount (by typing fdisk -l) , and i added this line to the end of the fstab file :

Code: Select all/dev/sda3 /mnt/2 ext4  users,noatime,auto,rw,nodev,exec,nosuid 0 0

(i had created /mnt/2 before ) ..... and this is the output of fdisk -l :

Code: Select allDisk /dev/sda: 465.8 GiB, 500107862016 bytes, 976773168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x4a373773

[Code] .....

After adding the line at the end of my fstab file , something strange happened , i rebooted the computer and mate didn't come up , it was a console like screen , i had to access fstab from there to delete the line and enter mate . i did this for 2 times and both times the same thing happened . How can I mount my partition permanently ?