Why did iran get its name changed to iraq?

Are you talking about Persia?
Because Iraq and Iran are still actual places, they are separate. 

If you're talking about what I am thinking, in 1935 the Iranian government requested those countries which it had diplomatic relations with, to call Persia "Iran," which is the name of the country in Persian. The suggestion for the change is said to have come from the Iranian ambassador to Germany, who came under the influence of the Nazis.