iPhone saying Sim Not Valid after I reset it

I have an iPhone 7 plus for over a year now. My phone used to work completely fine until at the end of January I decied to factory data reset my phone to restore some data I had lost. After my factory data reset completed, my sim card stopped working in my phone. When I turned my phone on, it said “Sim Not Valid” or an “Unable to Activate” message shows on the screen when I restarted it. It said that the activation server cannot be reached. I have tried everything but it won’t work. Is there anything I can do? I am attaching the images below of the two messages that show on the screen at various times I restart it.