Look guys, this problem has absolutely nothing to do with your Micro USB port and definitely doesn't require ordering a replacement. I had this same problem and it's usually caused because you pull your phone off the computer without ejecting it properly. Happened to me this morning, plugged my phone into my desktop in my bedroom last night and when I woke up for a meeting this morning, I just pulled it off without thinking since I'm used to it being on a charger at night and not hooked to the PC. Once I got home, every computer (I've got several) I hooked it to said USB device not recognized.
Go into your device manager, find all the entries for USB Host Controller or something with that in its name (mine specifically was Standard Enhanced PCI to USB Host Controller, on a Dell N7010). Uninstall each one of them (no worries) and shut down your computer. When you turn your computer back on, it SHOULD (on Windows 7 at least) automatically reinstall the drivers. If not, simply return to the device manager and right click on Universal Serial Bus Controllers and click Scan for hardware changes. It will reinstall the proper drivers and your device should hook up to the computer beautifully. THATS IT! No uninstalling/reinstalling Samsung drivers, no phone replacing, no trying another cord - none of that. None of those things actually have anything to do with the problem. You hear replace your cord so frequently but c'mon guys be realistic - if the cord was working last night why would it just stop? That's just silly and a waste of money. Try this out, works for me each and every time!
