What should I do after receiving a legal notice?

I was working at Macleods Pharmaceutical Ltd in Himachal Pradesh. I signed an employment bond for a 3-year period but was discontinued from my position after one year. I deposited two cheques in the company, signed but without writing the date. After one year, the company claimed the cheques, but they bounced due to insufficient funds. The company then sent me a Section 138 legal notice to recover the amount. I am unable to pay the amount, and the company stated that if I do not respond within 15 days, they will file a complaint accusing me of cheating and theft. What should I do?