I see that you're missing some icons from your lock screen. I certainly understand your concern and I'd be happy to help.
You'll want to be sure that you're using the most recent version (11.2) of iOS. As with any update, you'll want to be sure that you create a backup before updating.
How to back up your iPhone, iPad, and iPod touch
Update the iOS on your iPhone, iPad, or iPod touch
Once you have updated your iPhone, test it to see if the issue persists and let me know if it does.
Thank you for using Apple Support Communities.
Have a great day!