If you find there's a problem with your credit. Go get your three free credit reports from annualcreditreport.com. Look to see what is not accurate. If you find something wrong and the credit issuer won't take it off and the credit report suppliers won't correct your report than you're going to have to go down to the police station and file a police report. This will show that you're not liable and that you're serious.
Secondly you need to call all three of credit report companies and place a "credit freeze" on your social security numbers. I've had to do this and they now make it very easy. What this does is it now requires for anybody who tries to use your SSN to have them go through a series of very personal questions to prove that you are who you say you are. You'll have to reissue these every 6 months.
In the mean time shred every bit of personal information that you don't need with a cross cut shredder. Lock up any personal documents in a fire safe. Change your passwords regularly!