My sim card no longer shows even though it's inside the phone, the only thing that appears is no service, please how can I solve this problem ?

can you reset your phone? Does it allow you to somehow unlock the phone? If not press the volume up and down button and the turn off button and hold it until it allows you to swipe left to reset, if that doesn’t work, you would need to check with the service you are paying such as boost mobile, Verizon, or AT&T

Welcome to Apple Support Communities.

See: If you can't activate your iPhone - Apple Support.

For more help, contact your mobile carrier.

Jack

Contact Apple, then your mobile carrier.

See my response above.