Hi Nabeel,
you are entering 121214, and excel shows it 14-Nov-2231 (which is itself right)
you have to enter dates with proper way i.e:
12-12-2014
12-12-14
12/12/2014
12/12/14
12/Dec/2014
12/Dec/14
you will see the number 41985 if you format it to General.
also you can enter 41985 in any cell and then use date format.