Cannot use Windows XP Theme after making Changes

When you make a change to the Windows XP theme, Windows XP renames the theme
as Windows XP (Modified). You can easily return the default Windows XP theme at any time by choosing it from the steps below.

To use the default theme, follow these steps:

1. Click Start--> Control Panel.

2. Double-click Display--> Click the Themes tab.

3. In the Theme drop-down list--> select Windows XP--> and click OK to apply the default theme.