Hi,
The WINDOWS STORE is glitchy. It will actually report that the download resets to zero when in fact it is still downloading.
If you RESET then it likely just DELETED the files though.
Restart the download and just leave it alone until it finishes.
OTHER: you can also MOVE this to another drive (open "Apps and Features" from W10 start, find program, then move it to another drive if you have one. it will create a couple new folders on its own to move the game to)
There are other ways to cleanup and/or check file folders for size:
1) open File Manager, right-click the drive (i.e. C-drive) -> properties-> Disk Cleanup-> "cleanup system files"-> (may be large leftover files you can delete for Windows Updates or whatever)
2) program called "Folder Size"
http://www.mindgems.com/products/Folder-Size/Folder-Size.html (select the drive letter on bottom-left, then click the GREEN "play" icon)
You can then click the right side to organize from largest to smallest folders, expand on the left etc to go into subfolders