After downloading Lollipop 5, my sim card will not work. How can I get it working again?

[AC Question]

after downloading Lollipop 5 My sim card will not work

I got download from Android offering Lollipop 5 and downloaded but now I cannot make or receive calls - I get 2 messages Emergency calls only or no sim card and my O2 logo has disappeared how do I get it back again

 

[B. Diddy]

Re: after downloading Lollipop 5 My sim card will not work

Welcome to Android Central! Which phone? Have you already tried removing the card, then reinserting? Have you contacted O2 about this? They might want to try a new SIM.