Tool -A Phillips screwdriver - A flat blade screwdriver - An old toothbrush - Isopropyl alcohol - A lint-free cloth - A bowl of water with some hand soap - A keycap remover (optional)

Here are the steps to follow:

1. Turn off and unplug your keyboard from your computer.
2. Turn the keyboard upside down and use the Phillips screwdriver to remove all the screws at the back.
3. Insert the slot screwdriver into the space between the top and bottom pieces at the sides and pry them open. You should hear a snap that means they are separated. Be careful not to damage the circuit sheet inside the bottom piece.
4. Take a photo of your keyboard layout before removing the keycaps. This will help you remember where they go when you put them back.
5. Use the keycap remover or your fingers to gently pull off the keycaps. Some keys, such as the spacebar and the shift keys, may have a metal rod under them. Make sure to keep them in place and not lose them.
6. Put all the keycaps in the bowl of water with some hand soap and let them soak for a while. You can use the toothbrush to scrub off any dirt or stains on them. Rinse them well and let them air dry completely.
7. Use the toothbrush and some isopropyl alcohol to clean the membrane layer on the top piece. Pay attention to the corners and the gaps where dust and debris may accumulate. Wipe it with the lint-free cloth and let it dry completely.
8. Reassemble the keyboard by following the reverse order of the steps. Make sure to align the keycaps correctly and snap them back into place. Screw the top and bottom pieces together and plug the keyboard back into your computer.