Are you using a pirated version of Skyrim? (If you really are in Iran, my understanding is that all US exports to Iran are prohibited unless specifically licensed through the U.S. Treasury Department's Office of Foreign Assets Control, i.e most software released to the retail market since the U.S. started imposing economic sanctions is only available in Iran if it's pirated.)
If that's the case then no one can help you on this forum. If it's not the case then you may want to try reinstalling the game and reverifying the game cache.