printer automatically pauses jobs

I have a problem with print requests automatically being paused in Ubuntu 14.04 64 bit. The printer is a Canon MG3500 series connected wirelessly. It had been working, though slowly. I left it printing when the battery on the laptop (Lenovo Thinkpad T410) ran out of power and closed the computer down. Since then all jobs automatically pause and give no release option.

Can anyone advise what the problem is/how to change this, please?