Employer is refusing to pay me my final pay and I'm lost on what to do

I have been working somewhere for the last 3 months, and I have had some unexpected family illness for which I asked my boss if I could only optionally come into work on the weekends. They agreed and have been paying me by cheque, and since my last paycheck, I have only worked one day. However, it seems the arrangement doesn't work for them anymore, as I got completely replaced. I was never asked to sign an employment form, but I have plenty of messages, pictures of the paycheques, and proof of employment. I am asking for my final pay as in the last day that I worked there, but they are telling me that they cleared everything out, including my clocked in hours. Should I just let this go? What can I do?