Windows 7+ Theme Installer is a freeware from door2windows which lets you easily install new 3rd party Windows themes, apply & delete existing themes.
Apps from door2windows are truly free and DON'T include any offers to install 3rd-party apps/adware/toolbars/unwanted software and never will. The apps are portable and don't require installation.
Download door2windows App Bundledoor2windows App Bundle gives you access to all the latest apps released by door2windows in one download (along with future updates).
How to use:
Run the app. On the first run, it will ask if you want to patch the UXTheme files. Patching is required if you want to use 3rd party themes. If you haven't already patched the files (or if you are not sure), click Yes. After some time Windows will automatically log off indicating the patching has been done. Login and run the app again.
To install new themes:
Click the … button after .theme and browse for the theme file.
If the theme you want to install comes with replaceable system files, click the … button after the name of the system files and browse for the system file. In Windows 7, instead of TwinUI.dll, options to change Explorer.exe, ExplorerFrame.dll and OobeFldr.dll are available. The app will automatically make sure that the system file which you choose is of the correct Windows version and architecture. If not, you will see the following message:
After you have selected the .theme file and the system files that you want to replace, click Install Theme & System Files.
Windows Explorer will automatically restart and the theme and system files will be installed. Select the new theme in the list and click Apply Theme to apply the theme.
To restore the default system files just click Restore Default System Files.
To apply/delete existing themes, select any theme in the Installed Themes list and click Apply Theme/Delete Theme.
Credit goes to Manuel Hoefs for the UXTheme patcher.