Your printer may need to be reset. Disconnect your printer from your computer. Unload the sheets of paper from the feeder. Open the printer cover and remove the cartridges. While the cover is open, check for any paper jams or obstructions in the paper path and the cartridge carrier's path. If all is clear, close the printer cover. Unplug and re-plug the printer into the power source to reset it.
When the printer turns on, reinsert one cartridge first. Close the cover. Check for any errors. If no error, reinsert the other cartridge. Replace whichever cartridge is causing the error to appear. You can also try to reinsert a different known working cartridge to determine if the other is faulty.
For your wireless connection problem, you may need to reset the printer's wireless network settings first. Please refer to
How to Reset the Z1400 and Z1500 Series Network Settings.
To reconnect the printer to your wireless network, re-launch Lexmark Wireless Setup Utility on your computer.