Having read several threads, let me endeavour to outline the problem.
My computer: laptop running Win 7-64 bit
Tablet: Nexus 7 with latest update (which seems to have caused the problem)
Uninstall the driver
* done this twice
* there are five driver files
* WpdMtpDr.dll (c:\windows\system32\drivers\umdf)
* winsub.sys (c:\windows\system32\drivers)
* wudfrd.sys (c:\windows\system32\drivers)
* WpdMtp.dll (c:\windows\system32)
* WpdMtpUS.dll (c:\windows\system32)
* attempting to delete the file winsub.sys results in a message saying permission is required from TrustedInstaller. I don't know what that is, nor how to get permission. So, while I have been able to uninstall the driver, I have not been able to delete it.
NOTE: wpdusb.sys is designated as obsolete by Microsoft
Restart the devices
* first thing tried - to no avail
Use different cables
* done - no effect
Connect through different USB ports
* done - no effect
Change the Storage and USB settings on the tablet
* accessing the menu in the upper right corner only gives "Help and Feedback" as an option. There's nothing about MTP (whatever that is)
Yell, scream and swear
* done - gave me a headache
The device worked properly before the last system update for the Nexus tablet. The device now connects to the PC, and is recognised as being connected. It simply does not display any files.
I am an author and use my tablet extensively for writing. It is important for me to be able to connect the tablet to the computer and move files between the two. Please do not suggest work-around solutions such as Drive or Dropbox. I prefer to have devices that work properly.
Thank you for taking time to read this through and consider the problem. Please let me know if there is additional information that would be useful. Also, please be aware that I am not a developer and do not understand the jargon or shortcuts used by developers. Please be explicit when suggesting a resolution.