You may be able to fix this:
* Get some thick clear packing tape
* Apply packing tape in a single layer generously over dent
* Get a large spoon from the kitchen
* Put something like a bucking bar on the opposite side (to support against the pressure you're about to put on the skin)
* Massage dent using the spoon
* Watch magically as it starts to go away .. hopefully
I fixed a pretty bad one using this method.
Important! Be sure not to "massage" beyond your supporting "bucking bar" (or whatever you use) as doing so may create an impression.