My iphone 5 says invalid sim and it is not jailbroken

Then insert a valid SIM from a supported carrier... what's the question?

http://support.apple.com/kb/TS4148

You phone is locked to a carrier and when you put in a SIM from a different carrier you will get the message that you got

i got my iphone5 ios6.14 all is well I able to use it for hours but then couple hours later it gives me an invalid sim i already tried 3 different nano sim with different carrier but still nothing happens it always gives me a sim is invalid message or the carrier that i am trying to use is not setup for iphone that im trying to use why not when i able to use it before?..

Your carrier may have a software update to fix this problem. If you have not updated to the lastest iOS, then do this first. Then see if your carrier has an update. Apple also suggests you take your SIM card out and then put it back in; also to turn off, then back on various access functions, as well as the phone itself. The last has only temporarily worked for me. It's annoying and frustrating, but I look to the carrier software update as being the most logical explanation if you have had no problems with your phone and then this suddenly happened. (Like me.)