Printer problems. the printer stiops printing before the print is complete & the the cartridge

Question

the printer stiops printing before the print is complete & the the cartridge sticks wherever it stops.

what are the 3 buttons on the printer for
1 LH button has a cross onit
2 centre button, looks klike it should feed the pages, it also makes a test page
3 RH button, light flashes

none of the buttons do anything at this time