Loan how to deal with it

During the downturn my husband had very little work self employed fingers crossed that seems to be improving.
we have one loan that we had taken out when his company was trading this has not traded in the last few year and we were just about to get it struck off,company has not traded since around 2009 or 2010.

we have one loan of 6,000 that we owe through the company had forgot about it and there last week we got a letter from there seeking full repayment.we do not have the money for this...

Loan how to deal with it