Hi my phone is suddenly

It would have helped if you specified a little more...  I know a sim card is a little white card that holds memory and holds your phone number etc. Basically it IS your whole phone, and without it, you mind as well be holding a brick in your hand (haha).  So it is located in your phone underneath the battery. It is white and has a bunch of number on it. It is like a rectangle, but looks like one of the corners has been cut off.  It is very small.  What I suggest is that you look for it, and see if it is there at all. If it is there then you should check if it is inserted properly. I hope these help to solve your problem, best of luck! =)  *NOTE: Sim cards are not in all phones. Many phones are now "digital" and don't have sim cards. The two different types of phones are  called GSM and CDMA. If what I stated above does not help you, then please send me a message, as it is probably the other type, which require me to further explain.

Remove the back flap and reconnect attach the sim card.