Looking back at my tax record, I just realized that I have filed the wrong tax form. I was an international student from 2009-2011. In 2011, I have filed my income tax return and received a refund of about around $800. However it's only till now that I realized (filing my income tax return for 2011) that I have filed the wrong form. Now I am filing my tax abroad since I moved back to my country mid 2011. I would appreciate your help on this one, thank you very much.

To fix the problem, you need to a mend using Form 1040X and attach properly-prepared Forms 1040NR-EZ and 8843.