There are a lot of reasons that your credit may be in rough shape. Most are related to your spending habits. And, if you missed a few payments or your debt levels are too high—think over 30% of your total available credit limits—disputing errors won’t help you. You’ll have to make some changes to improve your credit scores instead. And you may have to wait a bit to see an uptick.
If you find information that is incorrect, you can file a dispute. Remember too, that items on your credit report that you don't recognize could also be potential signs of fraudulent activity — someone working to secure credit in your name for their own use. Make sure you're clear on items that could potentially be fraudulent, versus those that may simply be inaccurate.