Keep getting searching signal

I change hundreds of screens a week, this same thing happens to me but when I try making a call it works and says (searching) at the same time, try calling if you have not done so already, if its really not working do this,turn on your airplane mode for 10 seconds, then back on and power down the phone, not a hard reset, then power it back up, if that doesnt fix it go to settings, general, scroll to the bottom and touch reset, then reset network settings and go through with it, if that doesnt fix it and you are running with AT&T or T-Mobile then you should try a new sim, still not working then remove the logic board and scrub your sim reader with a toothbrush soaked with 90 percent alcohol, if still not working it's probably not fixable, good luck