I have a learning disability. And I can tell you that the shame is overwhelming. It is most likely what is keeping him from tying to learn. But if he has a really sever LD learning to read might not be the best option. Some people really never learn. So something like books on tape might be a good idea. But it all really depends on his condition. I would say that the number one thing is be gentle and understanding. Give him time to say that he might like to try.

Other than that you might look into private tutoring site like wyzant. Libraries also usually have adult community reading programs. So you can contact your local library. And you might also try reading to him as an intimate activity depending on how he feel about it. Doing that might make him more curious about reading in general, and help him come around slowly.