If you installed the Windows 10 Preview when using Windows update on your Windows 7, Windows 8/8.1 computer which you depend on and use for everyday tasks here is how you can restore your previous version of Windows.
The Windows 10 Preview has a “Rollback” feature that allows you to go back to (recover) the version of Windows installed on your PC prior to installing the preview.
If you were running an earlier version of Windows (Windows 7 or 8.0 / 8.1) then you can use this option to uninstall Windows 10 and restore your previous version of Windows without losing your earlier version’s applications, documents, photos and other personal files.
Note: Applications you installed and personal settings changes made while using Windows 10 will not be saved, however existing applications installed within your earlier version of Windows (Windows 7 or 8.0 / 8.1) prior to newly created Windows 10 documents, photos and other personal files will be migrated back to your earlier version of Windows.
You have three easy ways to access the ‘Recovery’ option:
Option #1) Click on Settings > Update & Recovery.
Option #2) In the ‘Search’ box enter: recovery options
Then click on ‘Recovery Options’ displayed at the top of the list.
Now click on the ‘Get started’ button in the ‘Go back to a previous version of Windows’ option to start the recovery process.
Note: If you see the following error message: “We’re sorry, but you can’t go back”, skip to the last part of this Wiki article for more information.
Read the fine print and if you still want to recover / rollback then click on the ‘Go back’ button.
Option #3) You also have a third method to rollback which is to click on the ‘Windows Rollback’ option displayed on the ‘Choose an operating System’ screen when you power on your PC or ‘Restart’ your PC.
When upgrading from a previous version of Windows (Windows 7, 8.0/8.1), you should see the following options. Click on the Windows Rollback option to start the process.
Now sit back and watch the action.
You receive the following error message when you click on the ‘Get started’ button:
“We’re sorry, but you can’t go back”
This error is the result of deleting the C:\Windows.old folder.
How did this folder get deleted?
A) You deleted the folder using Windows File Explorer. Typically this file is deleted because of the large amount of disk space it can consume as it contains the entire contents of your previous version of Windows or an earlier build.
Example: If your Windows 7 installation consumed 250GB of disk space due to a large amount of data files (Photos, Music, Streaming video, documents) then the Windows/old folder will be approximately 250GB in size. Depending on the size of your disk drive you may find that after installing the Windows 10 Technical Preview there is not much free space on your drive, therefor in an attempt to gain more free space the user deletes the C:\Windows.old folder.
More than likely the file will be too large to be contained in the Recycle Bin but you can always check if it’s there and if so restore it.
B) You ran Disk Cleanup and selected/clicked on the ‘Clean up system files’.