My HP printer wont print ..?

I've had the HP J4680for only a little while now and since switching to Cisco's valet I havent been able to print from certain computers and I don't know why! I've tried reinstling the program countless times and that used to work. Only recently that every computer has stoped being able to print and even reinstalling wont do anything...I need this printer ASAP for school what should I do? Can someone help me???