Today's assignment takes me to Mangrove Marsh to defeat a Thunder Horn Ghoul. Problem is I can not get in to Mangrove Marsh yet because my character isn't there yet. Why would you do that?
Oh my goodness this has been addressed SO MANY TIMES. It's extremely difficult to do these daily assignments in such a way that every single wizard at every single stage of progress in the storyline can do every single daily assignment. Only a handful of assignments per level bracket are available every day, and it would be way too much work for the poor devs at KI to make it more complex than that. KI has said that if you cannot do an assignment due to limitations in where you are in your quests, skip it for the day. You won't lose any progress and I seriously doubt there are any people left who have not missed a single day since the release of this feature- there have been bugs and quest limitations. Read the link below.
The assignments are set for a range of levels. They generally include areas that those levels typically have access to. Some players are higher level than usual for their area. If you can't access an area, just skip a day and wait for the next assignment, or you could continue questing and get to that area.
This happens from time to time for everyone. I get quests for Wintertusk and I haven't finished Grizzleheim. You do not have to do a quest every single day as there is not a penalty for not doing it on a day. You just continue where you left off. (That's the attitude of KI for now and while I don't necessarily agree with that approach, I personally am not bothered enough to change it. I've already gotten to a point where if it's a defeat an enemy quest I don't even do it.) It's based on the idea that most people of your level will have access to that location. So, I guess what I'm saying is don't worry, and you're not alone.
Today's assignment takes me to Mangrove Marsh to defeat a Thunder Horn Ghoul. Problem is I can not get in to Mangrove Marsh yet because my character isn't there yet. Why would you do that?
It happens all the time. Just wait for the time to expire on this quest. You won't miss anything; a new quest will begin right where you left off.