If you already have a good-to-excellent credit score and a low debt-to-income ratio, you may want to consider refinancing your student loans. When you refinance your loans, you take out a new credit-based private student loan and use the money to pay off some or all of your current loans. (The lender will generally send the money directly to your loan servicers.)
This story is long winded and all, but the point is, it doesn't matter how bad you have screwed up. It happens to the best of people (I'm an alright kind of guy). But the only way to fix it is to put your foot down, get dirty and fix it. It won’t always be as quick as this and will most likely take a year or more to get in a good place. Then years of maintenance. But if you need a quick hit to your score in a good way, read through your reports carefully (with a credit advisor if you need to. Many personal banks will do this with your for free if you have accounts there in good standing) If it looks like there's something off or something you can fix, call your broker, go over the report with them and STRONGLY insist on a rapid rescore. They will get all your info and see what they can do.
The key to debt consolidation is to avoid taking on new debt. If you borrow money, pay off your credit cards and then charge them back up again, you’re in worse shape than ever. If there is any chance that you might do this, or if you find yourself doing it after you obtain the consolidation loan, stop using the cards and just close the accounts. Your credit score will suffer, but your finances will thrive. Your score will come back up over time, and by then you’ll have learned valuable lessons about racking up too much debt.
What can and DOES change is whether you have a collector pursuing you for the debt. If you are talking about a dormant account that has been in collections and has finally been left alone with no collections activity for a few years, messing with it can be problematic from the point of view that the collections people will start pestering you again to see if they can get money and if the SOL isn't up, they can start reporting on it again which can affect your score or they could even file suit if your state SOL isn't up.
Each time you apply for credit is listed on your credit report as a “hard inquiry” and if you have too many within two years, your credit score will suffer. In general, a consumer with good credit can apply for credit a few times each year before it begins to affect their credit score. If you’re already starting with below-average credit, however, these inquiries may have more of an impact on your score and delay your ultimate goal of watching your credit score climb.