Hi maher-sharifa,
We see that you still have an issue with FaceTime and want to help. Have you used FaceTime in the past? Please know that FaceTime is not available in all regions. Please look at this article that talks about Wireless carrier support and features for iPhone in the United States and Canada - Apple Support.
You can select your region in the top portion of the article. If you do see your region and carrier listed there for FaceTime, is your iPhone updated to iOS 13.6? That would be a good next step. It is always a good idea to have a backup of your iPhone before updating.
Here’s How to back up your iPhone, iPad, and iPod touch - Apple Support
Here’s how to Update your iPhone, iPad, or iPod touch - Apple Support
Reach out to the community for further help if updating doesn’t help.
Best Regards!