There is no maximum number of uploads, except that you can only write the Flash maybe 10000 times (or more).
Have you tried to push the erase button for 3 seconds, then the reset button for 3 seconds then choose the correct COM port ( COM X (DUE Programming Port)) if you are using the programming Port., then upload your sketch.
Do not plug any external peripheral to your board when uploading.
Yes, I have tryed to erase and reset a lot og times.
The errors started some time ago, and then I user erase to get it to work, but it do not work any more.
I have uploadet maybe 500 times but not 10.000.