Once the Registry Editor is up and running, navigate to following key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths
Once you open the App Paths key, you’ll see a whole set of subkeys, each titled after an executable file. Now, as you look through the list of existing Run Command Shortcuts, you’ll see several subkeys named after native Windows apps, such as Wordpad.exe (WordPad) and Iexplore.exe (Internet Explorer). The reason that some of the Windows native apps appear in the App Paths key is that their executable files are located in folders other than Windows or System32. For example, WordPad is located in the Program Files\Accessories folder, and Internet Explorer is located in the Program Files\Internet Explorer folder.
To create a Run Command Shortcut for your favorite application, right-click on the App Paths key and select the New | Key command. When you see the new key appear, give it a two to eight character name—something that’s mnemonic or easy to associate with the application—along with an .exe extension.
Once you create the new key, you’ll see an empty String value labeled Default in the key. Double-click the Default value and when you see the Edit String dialog box, type the full path to the application’s executable file in the Value Data text box press OK to save.
Then using the run command just type php.exe and it should work.