Credit scores

start paying down debt as fast as you can. Pay small bills first, then pay off your smallest credit card, add what you were paying before to the next smallest card along with the payment you had been making for it, etc. etc. until you are paying as much as possible to the biggest bills. Then when your balance is zero cut each card you pay off up and don't touch it again. Pay your student loans the same way, apply all you can to the smallest first and get them off the books, keep working at the larger ones, don't leave any unpaid, a small attempt to pay something every month will show you are at least trying.
Sometimes open accounts, even if they are paid off will lose points for you, because it can be seen as potential debt. Payoff and close all your credit accounts except for one, and pay that off each month religiously once you get that last card paid down. Use that card only for emergencies, such as a breakdown on the road or emergency repairs to your toilet or roof. Stop eating out and cook meals at home, use the money saved to pay off debt. Quit smoking and or drinking and apply that money saved to pay off debt. If you can use public transportation or can walk or bike to work, sell your car. Never buy a new car, you lose half its value when you drive it off the lot. Get a good solid used car and maintain it properly if you have to have one. Go through your budget and controllable expenses to make sure you are living within your means and change your lifestyle to fit the money you have coming in. Downsize as much as you can. Apply all savings to debt. Set up a budget and stick to it. You can get financial advisors to help you, sometimes for free. Check out such financial advisors as Dave Ramsey and Suze Ormand and others online.
Talk to the bankers you have applied to and ask them what you can do to convince them to give you that loan and then follow their advice.
Get another job and use the money you earn to help pay off debt. Certainly there are things beyond our control, disasters, illness, sudden life changes of all sorts. But it is remarkable what you can accomplish with an object in focus and a plan to work toward that object. best wishes.