Q: the cellular Data is on same for the 3G is enable but however the 3G icon is not appering i can't text or go on the internet

I was using it last night everything was perfectly fine till i woke up this morning the 3G just dissapered and i've tried restarted the network. the 3G icon still havent showed up or anything what can i do to fix my iphone 4? I can't DO anything but i can use the wifi but i can't text or go on the internet without the 3G icon....