Silly question but have you been able to detach the door from oven first. If not depending on type of hinge. On my type of door you need to be in fully open position and if you look at the hinges there are two safety clasps one on each hinge lift this up towards you. Once the safety clasp is in this position you should be able to lift the door off as the hinges unhook from the frame.
Then follow the instruction in first answer.
DOOR HINGE LOCKED IN CLOSE POSITION BEFORE DOOR IS PUT BACK ON THE OVEN.
If you encounter this the safety clasp has slipped and the spring has sprung back the hinge going into the closed position. (You are not able to put door back on like this)
ANSWER
The springs are tensioned tight so you will not be able to pull it into open position with your hand. Pair of pipe grips and plyers needed. Hold the centre of the hinge casing between the two springs and use plyers to force hinge into open position. Then holding just the hinge, hook it into place in the frame of the oven and push it right down to the open position and pull the safety clasp up. Put the hinge back into oven door and place it back into the frame.
Chris Davies
January 2011