earlier my apple 4s was ios 5.1.1 after updating with ios6 from itunes my phone is not working please suggest me what to do

Sir i have connected my apple 4s with ios 5.1.1 version with my itunes. as and when i connected there was new version ios 6 which i have updated form ituned after updation my cell was not working why sir please let me know what to do earlier there was signal. now my phone is displaying contact your service provider where the sim is in working condition. is my phone locked or will it work what is the procedure to bring it again to working condition please let me know sir. ny mail address is bvbhaskar@gmail.com thanking you.