if you are using windows i have found that sometimes the usb ports u used for the phone get stuck to the driver that was there in the first place. So what I do to fix this is go into device manager from the control panel and then uninstall the drivers for the specific port that I am trying to use. While keeping my phone unplugged from the computer I then reinstall the samsung drivers, restart my computer and then try to plug my phone in. 90% of the time that has been what works for me.

Ok, I figured out the problem. It has nothing to do with the drivers or clearing ram memory. My problem is the actual micro usb connection. If is a little loose from side to side and when I push it to one side, it connects no problem.

That is the exact same thing that happened to my wife's phone... luckily it was still under warranty...

Sent from my SGH-T959V using Tapatalk

My phone is out of warranty. At least now I know the problem. It was extremely frustrating trying to figure it out.