Before getting started, let us explain the process to easily go through the required steps. Without activating Windows 10, Windows Settings shows a message –

You need to activate Windows before you can personalize your PC.

Also, the options are grayed out before activation. Now, if you do not want to activate Windows, and instead, you want to change the theme for any reason, you need to have the .themepack file downloaded from a third-party source or the official Microsoft theme repository. If you have an activated Windows 10, you can double-click on the .themepack file to apply the theme. However, if you do not have an activated Windows 10, you need to change a Group Policy setting called Prevent changing theme. However, you can do the same via Registry Editor.

Disable Prevent changing theme using Group Policy

To disable Prevent changing theme setting using Group Policy, follow these steps- To get started, press Win+R to open the Run prompt on your PC, type gpedit.msc, and press the Enter button to open the Local Group Policy Editor. After that, navigate to the following path- Double-click on Prevent changing theme setting on your right-hand side, and select the Disabled option.

Click the OK button to save the change. Read: How to create Custom Themes in Windows 10.

Disable Prevent changing theme using Registry

To disable Prevent changing theme using Registry, follow these steps- At first, press Win+R to open the Run prompt, type regedit, and press the Enter button. If it shows the UAC prompt, you have to click the Yes button to open Registry Editor on your computer. After that, navigate to the following path- Right-click on Explorer > New > DWORD (32-bit) Value, and name it as NoThemesTab.

By default, the Value data is set as 0, and you need to let it be.

That’s it. Read: Best free Dark Themes for Windows 10.

Change the theme in Windows without activation

Having made the changes in your Registry or Group Policy settings as mentioned above, now to change the theme in Windows 10 without activation, follow these steps- To learn more about these steps, keep reading. Note: These aforementioned steps are applicable only when you followed the guide to disable the Prevent changing theme restriction. Otherwise, it doesn’t work. To get started, you need to have the .themepack file, basically the Windows Theme file. Even if you have created a theme earlier, you can apply it too. Once you have the file, you can double-click on it to apply the theme on Windows 10.

In case you want to like to use a dedicated theme and want to turn on Windows 10 dark theme using Registry, you can follow this guide. I f you know where Windows 10 stores Theme files, you can navigate the path and delete the currently installed theme. However, there are some drawbacks to this method of changing the theme on Windows 10.

First, you cannot apply the default theme in case you want to revert to it.Second, you cannot change the color scheme.Third, you cannot select the wallpaper sources (Slideshow, solid color, normal wallpaper, etc.).

That’s all! Hope this guide helps. Read: This theme can’t be applied to the desktop error in Windows .