An attorney who is familiar with credit reporting will help you understand your rights under the law, especially the provisions under the Fair Credit Reporting Act. They will review your credit report and show you how much of the mix-up is there, after which they will be in a position to advise you on exactly what you need to do to disentangle your information from that of the other individual.
A proficient attorney can help by contacting the credit reporting agencies on your behalf to dispute any inaccurate or misleading information and ensure that the credit file accurately reflects your financial history. They can also represent you in your dealings with creditors and lenders to correct any negative implications that may occur as a result of the "my credit file is mixed with someone else's".
Although this is a complicated situation and frustrating, it's possible to do something about it. You can, with the help of an informed attorney, do all it takes to untangle the confusion and protect your financial reputation. Call an attorney to help you sort this out as soon as possible.