I have beaten the game and all but why is it im not able to travel anywhere after is it part of the game or am i glitched couse I got some companian quests i want to do.
Is too late! The game ends when the game ends, with the exception of downloaded content. Make a new character and play through again, or go back to an old save.
DLCs are the only thing you can go back and do after defeating the archdemon, unless you want to go to an earlier save and then go to Redcliffe Castle, Denerim, etc. again.