So no money was recieved you just did not have to make any payments. 

Dr.  Loan Payable for the principal amount. (thereby reducing your SBA Loan)

Cr. Equity.

Generally you would have credited Extinguishment of debt on the income statementdue to an extreme disaster but that would make it taxable.  Being this is a non taxble event you would credit your equity.  Also you cannot take a deduction on the interest being you did not make any interest payments.

Intermediate accounting.  Not often used.