An ex-employee refuses a reasonable settlement. What can the employer do?

Dear questioner,

I have an ex-employee refusing to accept or respond to a fair and reasonable settlement offer of a cash payment of 30% of his dues and 3 checks, payable over 60 days.

This is bringing the business to its knees as there is also a freeze on the company's trade license and bank account.

What are my rights as an employer to get the ex-employee to respond to the offer?