How to fix my iphone 5 on sim failure?

Please help me fix my iphone 5, before it gets ok when I just turn it off or eject the sim card tray or reset carrier settings but now it gotten worser I cannot get any signals anymore..no matter how I tried, I follow all methods seen in the internet still my phone has an invalid sim and appear as sim failure. Please guys help me out of these I just recently buy this from a second hand owner.