I accidentally dropped my Nikon 70-300mm lens and two small plastics broke off. Can it be fixed?
Lenses with plastic mounts are usually not worth fixing. If the lens covers a focal-length range you use frequently, consider seeking a replacement with a metal mount.
You'd have to replace the mount, but where would the replacement part come from? Likely another copy of the same model lens... which had also been dropped... which also has a broken mount...
- If the part comes from a working lens, what's the point of switching the mounts? It's a replacement, not a repair.
- The parts of different model lenses are usually not compatible.
There may be other damage that would prevent the lens from functioning.
Options to consider:
Glue the pieces in place, but it likely won't hold for long – rackandboneman points out – "If that ever comes loose in use and ends up in the way of the mirror or shutter, it can cause more damage than the lens is worth."
Glue the lens to a mount adapter to use as a manual lens on a mirrorless camera.
Sell as-is to someone who needs spare parts to fix another lens.
You could, potentially, repair it by gluing the pieces back in place. You'd need to use a glue that does NOT out-gas anything as part of the cure process; this to avoid contaminating the lens elements or anything inside the body. That still leaves you with the possibility, as noted by xiota, of the repair not holding and broken pieces in the body - you don't want that.
Replace it would be my recommendation. Toss it or sell it on Craigslist as a parts lens. It's a kit lens that can be bought at Adorama as a refurb for $110; $150 with VR. Both have plastic mounts, though.
Better still, buy into a better quality mount. Sigma & Tamron are good lenses and are notably less expensive than their Nikon counterparts.