@Raminnoorzai First thing is to reboot your phone. Then work through the suggestions here: https://support.apple.com/en-us/HT203302.
I assume that everthing else is working: calling, texting, browsing on cellular data.
BTW: You have posted to an old thread. In future you will have more assurance of help by creating your own topic on the forum (which I have done for you today), or sending a private message, when warranted, directly to the moderators.
>>> ALERT: I am not a CSA. Je ne suis pas un Agent du soutien à la clientèle.
