Very sorry to hear Normski. There are many kinds of loss to experience in this big beautiful world...
I personally believe I may have suffered some kind of very small stroke at some point. I can't say certain consonant combinations with my inner-voice, without great difficulty. words like, "caged," "changed." The, '-ged,' sound is something my mind just, 'can't do,' with it's inner speech, at least not without going very slow and exerting great mental effort. Fortunately I can say those words outloud with my speaking voice, still.
I've told family and friends about it, and they just think I'm nuts. I've been a heavy smoker for a while though.
Not that you wanted to know any of all that; but, if I'm not wrong in my theory about my queer malady, then, yeah, it's really weird/difficult/frustrating when some ability just goes, 'missing,' like a blank... (and probably quite devastating in severe cases...)
I hope you can, are able to, and will, continue to practice regaining function; as well as rely on what is still intact...
You might try learning morse code, sign language, etc..
I know I'm being overly optimistic and probably quite ignorant to something very devastating; but, I hope you continue to put that brain to use!
Good luck..!