If you choose to “Keep nothing” when you upgrade to Windows 8.1, or if you reset, refresh, or reinstall Windows, your personal files are temporarily saved to the Windows.old folder for 28 days (unless you formatted your hard drive before installing). If you decide you want some or all of these files back, you can usually retrieve them from this folder.
You can run a troubleshooter that will automatically retrieve your personal files from the Windows.old folder and copy them back to their original location. The troubleshooter will work on all languages but the text in the troubleshooter is only in English.
Run the recover personal files troubleshooter.
Swipe in from the right edge of the screen, and then tap Search.(If you're using a mouse, point to the upper-right corner of the screen, move the mouse pointer down, and then click Search.)
Enter Computer in the search box, and then tap or click Computer in the search results.
Double-tap or double-click the drive that Windows is installed on (typically, the C: drive).
Double-tap or double-click the Windows.old folder.
Double-tap or double-click the Users folder.
Double-tap or double-click your user name.
Open the folders that contain the files you want to retrieve.
Copy and paste the files that you want from each folder to a folder in Windows 8.1.
Repeat steps 5-7 for each user account on your PC.
To prevent data loss, we highly recommend backing up your files and settings to an external drive before resetting, refreshing, upgrading, or reinstalling Windows.
You have only 28 days to retrieve most files from the Windows.old folder, beginning from the time you install, upgrade to, refresh, or reset Windows 8.1. After that time, most of the content of Windows.old is automatically deleted.
Files and settings stored in the Users or Documents and Settings subfolders of Windows.old (including the default My Documents folder in Windows XP) might still be available in Windows.old after 28 days, but other files, including Windows installation files, will be deleted. If you reinstall, reset, or refresh Windows, the previous Windows.old folder is replaced by a new Windows.old folder.
For more info, see How to refresh, reset, or restore your PC and How to remove the Windows.old folder.