Do you have a wifi "toggle" in your pull down? My son has a S3 through at&t and does, but my verizon S3 does not. the last toggle to the left is bluetooth on mine, where he has a wifi one to the left of bluetooth
The only way to get it back (currently, anyway) is to root your phone and install a 'patch'. You can find more specific information on both of these topics in various stickies and threads within this forum.
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