You can go to the irs.gov website and click on "Where's my refund". This will tell you the status of your federal refund for the current tax year. Here is the link that gets you to the correct webpage. http://www.irs.gov/individuals/article/0,,id=96596,00.html?portlet=8 Click on Where's my refund? and put in your information. You will need to know your SSN, your filing status, and the exact amount of the refund you are awaiting.
If it is your Michigan state return, here is the link to that one as well. http://www.michigan.gov/taxes