If you are denied credit based upon your credit score or what is on your credit report you can get a free copy of your credit report, even if you have already gotten the free report you are entitle to every year.
But do not delay.
You only have 60 days following a denial in which to request the report from annualcreditreport.com.
If you were denied because of a mistake on your credit report, you can dispute the mistake and you should be able to get it removed.
Send a letter with documentation to the credit bureaus and they will need to respond within 30 days and either justify their listing or delete it completely.
However, really getting results from disputing your credit matters may take experience and expertise along with time and energy. You may want to consider contacting a professional and reliable credit repair company to assist you. If you do make sure that you check out their credentials with the Better Business Bureaus and that they are compliant with the CROA.