We've had this occur in the past after joining certain guilds. If you happened to join a guild recently, that may be the cause of it.
The workaround is to swap the game's language, log in, and drop out of the guild you most recently joined. To change the game's language, click on the gold cog in the top-right corner of the launcher and change the language from the drop down menu. A short patch will download to update the dialogue, and you can then log in.
Once you're in, if you're able to make it beyond character selection give a shot to dropping out of the guild and swapping the language back to your preferred language. If you're not able to get beyond character selection, let us know and we'll be happy to do what we can.