Bankruptcy is a form of insolvency, that is, a declaration that you are insolvent.
It can be either voluntarily by application yourself or involuntarily by a creditor(s) to whom you owe money.
Once made bankrupt, responsibility for your estate will be taken over by a trustee. This trustee will either be an official receiver (an officer appointed by the bankruptcy court) or an insolvency practitioner.
A bankruptcy will usually last a year, after which you will, for all intents and purposes, be able to start over financially.