A computer repair customer of mine brought to me a Hewlett Packard Laptops model 15AC121DX. I am going to describe what you need to do to remove the hard drive in this notebook computer. First you will a philips style screw driver.
First you want to remove the laptop battery. There are two releases one on each side of this battery. Once the laptop battery is removed, there are two screws underneath this battery.
Remove those two screws plus another ten screws. Two of the remaining ten screws are hidden under rubber feet on each side of this laptop towards the rear. Once you have all twelve screws removed you can take this bottom cover off by just pulling the cover up towards you while the laptop is face down.
The hard drive is located towards the left front. There are two small screws holding this hard drive in place. Remove those two screws.
Now you can pull the hard drive out. The hard drive is connected to an adapter that connects to the motherboard. You can just pull this adapter cable off.
It is attached near the SATA and power connectors on the hard drive. There is one metal bracket attached to one side of this laptop. If you are replacing this hard drive you will need to transfer this metal bracket to the new hard drive.
There are two small screws that hold this metal bracket in place. Make sure the metal bracket is attached to the hard drive on the correct side so that the SATA and power connectors face towards you when reattaching the hard drive adapter cable. Remember to screw down the hard drive with those two small screws.
Place the back cover back on. Remember to tighten the two screws under the battery. Insert the laptop battery back in its place.
Slide the optical drive in its slot. Now you just need to tighten the ten remaining screws. You have successfully replaced the hard drive on a Hewlett Packard Laptops model 15AC121DX.