When i got my gs3 i plugged it into my computer (Win 7) and drivers installed automatically. everything was perfectly fine i was able to access both sd and phone from my computer. i took it to activation with clear talk and it didn't recognize usb. I have reinstalled proper drivers from samsung web page. i have also tried kies. kies wont accept it. I have tried it on linux and didn't work. Both computers recognize phone but phone wont recognize computers. The thing is i won't get the option of mtp or ptp on the drop down notification menu. this is not a matter of drivers or usb debugging. i have tried to remove battery for 1 min and reset it. any ideas how to fix?
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.