Have removed the oven door of neff b1422 oven and can't get it to re-attach. The 2 metal hinges on the door keep closing when I line the door up with the oven itself, which results in the door just staying in place for a second before falling loose. I have followed the instructions in the manual with a negative result.

The inner door glass is usually lifted out by removing the two plastic/metal clips at the top of the glass, in the corners.
The glass cannot be glued in. How are you going to clean it if you do ...

I have the same model Miele and ordered a replacement part. I have 2 Miele ovens side by side, and a door hinge on both ovens began to malfunction. I ordered and received the hinge , but when I started to install it, I found that the hinges were fine! The issue was that the 3 screws that hold the hinges to the oven frame came loose. One of them had fallen out on each of the doors, they had to be jiggled in order to close properly, which was not satisfactory. The ovens were installed 13 years ago by the original owners.

You will need to slide the oven out of its enclosed space and unscrew the sheet metal siding in order to gain access so that you can unhook the coil spring attached to hinge. I found that one of the small machine screws has fallen out on the 2 malfunctioning hinges. Once the spring is unhooked, you can align the hinge to screw it back in, and tighten the other screws that hold the door hinges. The screws on the other side has also become loose.

fully open door and lift up small metal stirrups on bottom of hinge then close door up to them grip door firmly and lift upwards ,there are videos on you tube for this also.

The inner door glass is held on by two clips at the bottom (hinge side) and two slides near the handle side. Remove the door from the oven and lie it the worktop flat with the hinges uppermost. Near the hinges you will see the glass is angles leaving a triangle of metal frame either side near the hinges.Rest the outside of your hand on the metal for purchase and then pull on the glass along the bottom edge (reasonable tug required) this will disengage the bottom clips and then slide the glass down about an inch to remove completely.

I would have gone straight through Neff. If it can't be fixed, your'e supposed to get a new oven out of the deal.

The simple answer is yes you can buy new hinges,
There are several places on the net where you can buy these.
Just enter NEFF oven door hinges in your web browser, and you should be able to choose from many listed.

Open oven door. Flip metal holder down at hinge to lock hinge. Lift door with hinge attached up slightly and off oven. Reverse to re-install door, making sure notch at bottom of hinge is hooked in frame of oven properly.

Yep, sounds like the hinges/springs have been overloaded.
Dont know if it's a Neff problem in particular, but I had a Neff oven with exactly the same problem - it was already installed when I bought my house.
Spoke to Neff who advised this ocours if heavy things like a roasting tray with a heavy bird / joint in it is rested on the door whilst it's open.
Only cure is new spring/hinge units which are not cheap !

You need to replace the oven door hinges.
Please rate my solutrion.
Thanks.

you need to lock the hinges to get the door back.
it needs some strength
lay door flat on floor
force hinge against the spring until right back and put the locking arm over. i use my feet for this!