Hi Arnorf,
Thanks for using Apple Support Communities. It's our understanding that the keyboard click and lock sound aren't working on your iPhone. You've done a great job so far. We're here to help.
If you haven't already, go to Settings > Sounds & Haptics, and make sure Keyboard Clicks and Lock Sound are on.
If the issue persists we recommend restoring your iPhone to factory settings. We definitely don't want to risk losing any of your important content, so be sure to back up before trying this step.
How to back up your iPhone, iPad, and iPod touch
Restore your iPhone, iPad, or iPod to factory settings
Let us know the results. Please include specific error messages and any other troubleshooting steps that you may have tried.
Have a great day!