Having trouble with my Pixma mx870 printer

Im trying to print somthing but my computer cant connect to my pixma870 printer it has a support code saying 300 the printer erly connected to your computer. I checked the wifi on my printer its ok but i dont know why it dont print. I called the tech support they said they dont support my printer no more. Im so mad coz how come canon cant help a customer even my printer model is not that old. Canon should still support it now i dont know what to do i have school documents that i have to print and indont have money to buy a new one pls. Help