I lived in Memphis, TN from January until June of 2007 then from August until November of 2007. I worked in Tennessee and also in Mississippi, so I received my forms from those respective states. However, the months I didn't mention, I lived in Illinois. I also worked in Illinois and Indiana. So I also have forms from those states as well.

As you can tell, it is very confusing. A cousin of my wife did my taxes and I received an amount very small that I believe is not right. How do I go about seeing if he did my taxes correctly? What is the process to filing taxes from so many different states?

Where did you live in Dec 2007? If your lived in TN, then TN is your tax home.

File tax returns for Mississippi, Illinois and Indiana and pay tax only on the income from a state while working in the state.
For TN return, report all your income for the year. Then claim credit for taxes paid to Mississippi, Illinois and Indiana.