You can change your game text language in Age of Mythology to any of the supported languages for which you can find language .DLL files for (English/German/French/Russian etc.). To install a different language game text all you need to do is replace the following files in your root Age of Mythology installation directory with the ones provided in the text language packs below:
xpacklanguage.dll (if Titans is installed)
Language files for the game taunts seem to be much harder to find. To change your game taunt language you need to completely replace the following directories (located in you Age of Mythology installation directory) with the ones in the taunt packs:
sound\xtaunts (if Titans is installed)
If you’ve followed the above steps and are still having with the Age of Mythology change language issue, please post in the comments below. To increase your chances of a solution being found include as much detail as possible (which version of the game you’re running, what operating system you have, what video card you have and steps to reproduce the issue). Screenshots are also very useful!