The economy goes south. Banks get nervous and raise their loan standards. Yesterday, you could have borrowed money, no problem. Today, loan officials just shrug and shake their heads.
You've become the victim of a financing squeeze. Or a credit crunch, as it's sometimes called.
An economic situation comes up that forces banks to restrict their lending. Lenders start refusing potential borrowers to whom they would have previously issued credit without much trouble. Meanwhile, the people who are able to get loans have to pay higher interest rates for the privilege.
A financing squeeze has the impact of worsening the economic situation. Money can't move around as quickly as it could before. Fewer loans mean less cash to start businesses, and less money to spend on things like cars or new homes.