Samsung Galaxy S3 Won't recognize USB
After frustrating research i found the solution. the guy who flashed my phone from us cellular to clear talk messed up. 
soulution
Open Dialer enter *#22745927
When Enable/Disable Menu comes up tap "Hidden Menu Disabled"
Select "Enable" on Popup
Press Home button
Open Dialer
Dial **87284
When PhoneUtil Opens Select PDA
Tap Qualacomm USB Setting
Select DM+Modem+ADB
Tap OK
(Remember after flashing to return and put phone back to MTP+ADB)
All props go to this page
http://forum.xda-developers.com/showthread.php?t=2270191 
there is other devices listed there as well.