unable to access iphone after IOS 7, error as SIM not Valid

Generally this is a sign that the iPhone had previously been

hacked/modified/jailbroken and the update relocked it to the

original wireless carrier. If this is the case, only that wireless

carrier can unlock your iPhone. You must contact them to see

if they offer unlocking and if you qualify.

Where did you acquire this iPhone?

What wireless carrier did you use before this problem?

Does the app Cydia appear on your iPhone?

What does it say when you look at Settings=>General=>About=>Carrier?

Unauthorized modification of iOS