My printer started to only print random numbers and letters MODEL HP DESKJET 840C

your cartridge must be replaced
the printhead of the cartridge is bad

Return the cartridge and get a refund, it's defective. Make sure you buy brand-name cartridges, too.

Friend try the utilities through cleaning nozzle check and head cleaning

Dip the head area of cartridge in hot water by 2 to 3 seconds two or three times and use tissue to check the color, if all three color comes out to tisssue paper, then it works else you have to replace the cartridge.

Ahmad Bilal

I have no magenta trying second cartridge still same problem

There should be some error .So you know how to remove the catridges just remove it n re insert it properly.If there are any paper jams try removing it also.and by the way if you haven't installed the drivers for HP deskjet this problem may arise.So make sure you ahve don this.Also this can be happened if the printer have some hardware problems.So none of this solutions are working its better to consult it with an expert.

you don't "make" an envelope. That little envelope picture on the tray is so that you can print on an envelope. you usually do that from Word under "labels and mailings"

cos green color is out. what u do is refill the color catridge or rather buy a new color catridge n ur up again.
hope u find help here
thank u

pls. change your data cable of printer connected to computer

if it is work pls. remarks

hi i am having roughly the same problems i use cad and have not even managed to print that far yet what windows are using?