I have a couple that look pretty much like that. First off Sew-Classic {
http://www.shop.sew-classic.com/ }
sells special abrasive cord to polish out nicks and gouges in needle plates. I'd get some of that.
Then I'd go to somewhere like Harbor Freight and get a couple different sets of jewelers files. Some of the files are down right tiny.
Then using those I'd remove the metal that has been pushed into the needle hole. After that I'd polish the edges as best as possible without making the hole larger.
If you have a find knife sharpening stone with good corners on it you can also break the edges with that.
But even after all that work, I think the best idea is to replace the plate.
Joe