Read the letter the IRS sent. It probably states that someone else claimed you, and if you are entitled to claim yourself, do nothing, but if you claimed yourself in error, to file an amended return.
Bring the IRS letter to a tax professional and let them tell you what to do. If it says to amend your return, let the preparer do it. Be sure to bring a copy of your original return. If you don't have one, you can get one from your local IRS office. A printout is free.
Snipes