Company not a going concern

I prepared accounts for a client in October/November last year on a going concern basis but was asked not to file them in case the company proved not to be a going concern. A sale is currently being negotiated for the business of the company at a significant loss. Should I therefore amend the accounts to a break up basis and how should I value the business when the final figures have not been agreed?

Any suggestions would be gratefully received.
Thank you.