This happened to me following a concussion. I worked with a therapist who suggested a "game" that could help my word recall. Every night before sleeping, pick a category and try to name an example from the category for each letter of the alphabet. Choose a different category every night so you're always challenging yourself.

Of course there's no substitute for working with a PT who specializes in post TBI recovery.

I've gained a lot of my recall back (though not at 100%).