character party stuck

Please help me. my 2nd character stuck on instance (Druidcaboels). cant invite people to join party / cant accept invitation from other player.
i was random dungeon finder heroic ( solo ). then after last boss. i was use heartstone to get back, because they'are all leave party and i cant out from dungeon. thats why i used heartstone. then when i want to invite my friend there's text like this. ( is not in your instance ) please reset it sir. i cant rdf hc / gear up fos party dungeon.