J'habite un pakistan

Hello Hira,
Pakistan is a masculine country, therefore you need to use "au" as such:
"J'habite au Pakistan."

Have a look at the matching lesson:
https://www.french-test.com/revision/grammar/use-en-with-feminine-countries-and-aux-with-masculine-countries-to-say-in-or-to-prepositions

Hope it's helpful !