The battle for undercity. I can not solve the problem of this mission in any way

Hi. Excuse my bad english The name of my character is gemo. i try Complete the chain of missions "the battle for undercity"(horde) and to want to finish it bugg in the last mission. Now I can not see the NPC or the people of Ogrimar and undercity. please help. I can not continue playing like this My head hurts trying to fix it on my own.
please. Try everything. Until he changed factions. And I can not remove or end this chain of missions. If some GM can delete it or remove or fineñizar as soon as possible to help me because I am going crazy. thank you very much. I await your help. An old player.