A lot of people like to think poorly of a plastic mount on a lens, but I will say in most cases I would rather break a bayonet than a camera or a whole lens. Maybe this is why most kit lenses have plastic bayonets.
I thankfully did not break this lens. I bought it in eBay for about 20€ with a broken bayonet. A broken bayonet that I knew I could repair. As you can see from the images that two of the flanges had been broken off in a light fall and the lens was listed as working but defective because of the mount. I knew I could replace the bayonet or glue it up and have it work until I could get the part shipped to me.
So things you will need
1. Broken lens
2. Super glue ( I suggest brand name and the gel type )
3. A third hand or helping hand depending on the nomenclature you are used to.
4. Patience, this will go wrong fast if you rush anything.
Step 1: Gluing the Flanges Back On
The first thing you want to do is apply some superglue to the body of the bayonet where the flange has been broken off. I used a toothpick, but that isn't necessary. Then I let it set up for a few minutes. Then I put the flange in the alligator clip in the end of my third hand and firmly pressed it in place. It's best to let it set up a good 30 minutes to an hour before starting the second one.
Step 2: Reinforcing the Flanges
So since I want this to last until I can have a new bayonet shipped to me, I need to make it stronger.
So I added some more super glue to the inside of the bayonet. Since this is a place that doesn't move and isn't a place that comes in contact with any other part, I could liberally place a faire bead of glue.
I suggest doing this and letting it dry and repeating as you do not want the flanges to move or flex at all.
Step 3: Let It Set Up
After waiting 24 hours I must admit that I did the third step a second time and I also added a little with a toothpick under the flange as well. I do need to stress that doing this can change the tolerance of the mount and could make a problem for mounting the lens correctly, so use a liberal amount of caution.
Step 4: Enjoy Your Lens
Everything works fine and it mounts securely, I have been using it for more than a week now with no issues.
Now everyone's mileage may vary of course and I would never say that this is a permanent solution. However when done properly, it should last long enough to get a new bayonet and install that. That way you still have a functioning camera even if you don't have more lenses.
I claim no responsibility for anyone's failure and I only put this here to help people in a pinch. Best wishes and good luck!