If that happen to me I would of used an alt character to lure the boss away from my body and then log out when the boss is far enough away. Then I could log into the main character equip and eat and retry. The alt character doesn't need any equipment but eating stamina food will allow them to run away better.

Another thing you could do is have your main charaacter go to a different world and get some things then return to the world where the boss is.

Or just have some strong guy log into your world and stomp the boss as others have said.