The MP160 must be turned on AND connected to your computer. Then the printing head moves to the left hand side.
Remove cartridge by pressing down then draw out towards you.
Refit by inserting and pushing up. THIS IS VERY FIDDLY
good luck

If yours is a C4150/80 HP Scanner, Copier, Printer all in one.
1. Look at the front of your 4150: you have a place to feed out the paper and to the right of that is a smaller compartment. Above those areas is a small "lip" that you can use to raise the top of your
all-in-one.
2. This activates the machine to place your cartridges to the right side of the machine.
3. Open the small compartment door to the right (on the front) by pulling it down.
4. You'll see two cartridges:One is the color and the second is the black ink. Pull straight out on the selected cartridge to remove it. It takes a little effort.
5. Once removed, take the piece of paper off the new cartridge and put it on the old one in the exact place it was on the new.
6. Put the new one in until you feel it click. Shut the door on the front compartment, close the lid on top of the machine.
7. The machine will now run a series of adjustments and print a test page.
8. Check the page to assure all bars align.
9. Place the old cartridge in the small envelope HP provides and mail it back to the company. It already has been "stamped" so no extra funds involved from you.