Have you signed any Bond undertaking to work for a minimum period of time in the organisation failing which certain amount shall be paid? Cheque cannot be taken in lieu of a Bond.Whether the cheque is blank cheque or amount was filled up. When you fell sick, did you atleast inform your employer by mail about your impending absence?
Most probably company may decide not to chase you with a court case etc as it is waste of time for them. Instead they could have hired a new person by now. In case you have signed a Bond, Company may try to file case, which I feel is a remote chance. But if they file a case based on a bond signed by you, you have to face the conceqeunces.