Quel'Delar gone on last quest

Hello Support,
Well my issue is with the quests about Quel'Delar.I started the quests before 2 days and yesteday I was on my last quest.But on the last quest of Quel'Delar "The Purification of Quel'Delar" u need to get 0/1 restored quel'delar and when i left it in the Sunwell,I waited for the 2 Mobs conversation and they said that I need to loot him and finish the quest,but the problem is that i looted him and I could not pick him up and soon after 5-10 minutes trying the sword was gone from the Sunwell.I dont have any item left from it and I was on the last quest (only got the quest).Please dont say that i need to farm the item again to start the Quel"delar quests again.
Please help me,thank you :)