Hi Tirona_1111,
I understand that the bar at the bottom of your Lock screen disappears intermittently and you have to restart your iPhone to get it to appear again. I can see why you'd reach out about this behavior; I'm happy to help. Based on the behavior you've described I'd recommend that you create a recent backup first: How to back up your iPhone, iPad, and iPod touch
Next, use the steps titled "Put your device in recovery mode and set it up again" in the following resource to reinstall iOS to your device. This process will erase the software currently installed and replace it with a fresh copy; be sure to closely follow step four and choose to "Update" in order to prevent data loss: If you can't update or restore your iPhone, iPad, or iPod touch
Take some time to test for the behavior after reinstalling iOS and let me know what you find.
Best Regards.