Hello bedu,
Thanks for that info and for choosing the Apple Support Communities. If I understand correctly, you are having an issue with your iPhone being unexpectedly unresponsive. First, make sure your iPhone is up to date, as the updates contain stability fixes that can resolve issues like yours, as well as important security updates to keep your iPhone safe.
Update the iOS software on your iPhone, iPad, or iPod touch
If you're still having this issue, your next step is to reinstall iOS on your device; this will help us isolate the situation further. Reinstalling iOS should not affect any of your data, but it is always a best practice to make sure you have a current backup in either iTunes or iCloud.
How to back up your iPhone, iPad, and iPod touch
Transfer photos and videos from your iPhone, iPad, or iPod touch
Once you have a current backup, follow the steps from the "If your device turns on but gets stuck during start up" section in this article:
If your iPhone, iPad, or iPod touch won't turn on or is frozen
Use the “Update” option and not “Restore” and these steps will reinstall iOS. Keep in mind that these steps were written for a different issue, but they will still help us isolate the situation further.
Cheers!