My cheque, issued on July 9th, 2016, was valid for three months. It was presented on time, but I haven’t received a demand notice yet. Can I still send one, or is there another way to get my money back besides filing a lawsuit?

Since your cheque was presented within the three-month validity period, you can still send a demand notice to the drawer. You can also approach the bank where the cheque was presented and request them to initiate recovery proceedings on your behalf.