Hello- My sister didn't need dropbox and uninstalled it. PROBLEM: Windows 10 can no longer access certain folders including Downloads, Desktop and Documents in the Dropbox folder under User account. Try to copy, delete, cut (whatever) and you get Error 0x80070780 (file cannot be accessed by the system). In trying to fix problem I may have made it worse: 1) I reinstalled Dropbox and during install I believe I told it not to sync; 2) I opened sister's online dropbox account and I believe I told it not to sync; 3) I uninstalled dropbox from windows 10; 4) I logged back into sister's online dropbox account and deleted it; and 5) I also tried SFC and other system repairs, but no luck, the problem still persist. I now think I should have unchecked the backup options in preferences before dropbox was uninstalled the second time. Since I deleted my sister's dropbox account (oops), I'm not sure if I can go back and reinstall dropbox to make things right? I have a backup of all the files (folders) but I can't delete those dropbox related files on her local computer, again Error 0x80070780. My last resort may be to search and delete every instance of dropbox in the Windows OS registry. I need to fix this problem, please let me know if you have any suggestions? Thanks in Advance Bill
MY Solution to Uninstall Dropbox and Restore PC to Default Setting:
1) Using File Explorer, I copied the folders Desktop, Documents and Downloads (located in C:\Users\Kathy\Dropbox\PC-Kathy) to USB drive. Next, I copied the folders Desktop, Documents and Downloads located in C:\Users\Kathy to USB drive. Lastly, I made an image backup of the C:\ drive (system drive) using Macruim Reflect (free ed.). In this case both User and PC are named Kathy.
2) I right clicked the dropbox app and went to preferences to un-sync all folders. There may have been a backup option, if so, turn it off. Using a browser, I went to the online dropbox account and under settings I un-syn'ed everything. After that I deleted the dropbox account. Not sure it matters, you may want to keep your dropbox account.
3) Next I uninstalled the dropbox application from the PC.
4) Under C:\Users\Kathy\Dropbox\PC-Kathy, I believe I deleted the folders for Desktop, Documents and Downloads and sent them to Recycle Bin. Using the backup files (above), I copied the relevant folders from the USB drive back to C:\Users\Kathy\Dropbox\PC-Kathy. Alternatively, I may have recreated the folders (under C:\Users\Kathy\Dropbox\PC-Kathy) [as new empty folders] and copied over the files from each of the backup folders, not sure now. ;-(
5) Using File Explorer, I navigated to C:\Users\Kathy and renamed the Desktop folder as Desktop1. I did the same for Documents and Downloads (renamed them Documents1 and Downloads1). I then navigated to C:\Users\Kathy\Dropbox\PC-Kathy and moved Desktop, Documents and Downloads to C:\Users\Kathy\. Just grab and move.
6) Next, I opened up File Explorer and under "This PC" I reviewed the folder settings for Desktop, Documents and Downloads. Right click on the Desktop folder and look at its Location tab (upper tab). In my case, the default location is C:\Users\Kathy. If the Desktop folder doesn't have the default target location, you can move its location (Note: say no to moving apps or files, just move the target). I did the same process for the Documents and Downloads located under This PC.
7) Lastly, I went back and deleted the dropbox folder located in C:\Users\Kathy.
Yes, I believe I "unlinked the connected device" (Kathy-PC) in the online dropbox account. I probably have more steps than needed. Most important part may be setting the target folder locations for Desktop, Documents and Downloads under "This PC".