Euro cylinder has fallen out, opening the door

[bysantium]

Hi, I tried to replace a cylinder on a high security door (no credit card tricks for opening possible). Obviously I put back the screw holding the cylinder, but I didn't realize that it did not go through the cylinder itself . Next day I wanted to put my key into the cylinder, but I just pushed the cylinder through the door. From my side the lock mechanism has a rotating, protective plate in front of the cylinder. This prevents me from putting a new cylinder into the lock and there is only a slightly larger slot on it than the key itself.
The door is closed and I can't get the key into the cylinder and I also can't put a new cylinder into the lock. I can see the pushed in cylinder, far away from it's working position.
I'm quite familiar with locks and lock picking, but now I'm just scratching my head! I have no cylinder and I still can't open the lock. The narrow slot on the rotating plate is too small to insert bigger tools and the usual lock picks are useless.

Any suggestions please?

Thanks !