Laptop's key not working

Gently pry off the spacebar keycap (use a thin plastic tool). Clean underneath with compressed air to remove dust or debris. Check the metal stabilizer bar and rubber dome — if misaligned, reposition carefully and snap the key back on.

If cleaning doesn’t help, you can replace just the spacebar key kit (keycap + hinge + rubber) instead of the entire keyboard.

Well I will suggest you update the keyboard driver sometime outdated driver can also be the reason for this issue so make sure your driver is updated to it's latest version.

There’s no easy way to fix broken keys. If it’s broken, you’ll need a new top cover part. HP keys can’t removed and reattached. We just swap out the top cover with keyboard, which means all the other parts, including the motherboard and the LCD assembly has to be transferred over to the new top cover with keyboard.

If there was an easy way to fix just one key, HP would have supplied to means and parts to save cost. They don’t, so we replace the entire top cover instead.