When I plug the USB on my galaxy s3 sprint it charges normally but no notifications appear about using the mass storage.. so how can I fix that and transfer the data from PC to my phone. NOTE: I cant find this option connected as media device one the notifications.
OS: Win 8.1 x64 with latest updates. Phone: Samsung galaxy S3 (GT-i9300).
I got it working without manually installing any driver. When I plugged my phone in the computer it automatically installed the driver for me. After that I didnt see any popup. What you need to do is leave the phone plugged in your pc/laptop while restarting the phone (don't be to hasty here, give the phone some time to boot up completely). After that go to control panel > Hardware and Sound > Devices and Printers. In here look for the multimedia tab and you should see your phone (GT-i9300). Right click on it and you should see the menu browse files > GT-9300. Voila you are in your phone.
After that you don't even need to repeat the steps before again, because the popup suddenly comes back(don't switch to another usb port here, just keep using the port where you performed your phone reboot). Incase you accidentally plugged your phone in another usb port you need to repeat the steps above.
Thats how I got mine working. I hope it helps you!