iphone answer button not appearing help me

Hi guys, I have a problem with my iPhone. Every time when someone calls, I can’t respond, because the “answer button” doesn’t appear, I only here the ringing. I also can’t call people. I tried to turn it off, but it doesn’t work. What should I do?

Backup your data.
If your IOS version is less than 14.7.1 then update the IOS

Do this https://support.apple.com/en-us/HT201412
Forced restart. It is good for a lot of things, not just Wyatt this article states. We do this for app issues as well. There is a good chance this will resolve this issue.