Bad credit basically means that you are considered an unsafe person to lend
money to, ie you will probably not pay it back. If you have been told that you
are a bad risk and have been refused credit, the first thing is to establish
whether it is true. You can ask the company why they refused you credit and, if
their reasons are incorrect, you may be able to get the record straight.

However, if you really do have a history of unpaid debts, the only way to change the situation is to start paying regularly. You can't clear your history - your record will unfortunately follow you around - but it is possible to get help with managing your debts, usually by putting them all together and agreeing to pay off a manageable amount each month.

The best place to start looking for help is the official government site for debt management advice.