I'm hearing impaired so I like to buy DVDs that have CC/SDH on it but several I bought (new and sealed) don't have it even though it's indicated on the cases.

Why would they say they have it but doesn't?

When I buy some used I know I'm taking a chance because the cases didn't have the original DVDs they came with even though the titles matched.

If it says "SDH" they should come on when you hit the player's Subtitle button. Some of these (such as ones from Disney) also have traditional TV-decoded closed-captions, but generally SDH means it's a subtitle track. Of course the old-style closed-captions have become more and more complicated to display on modern equipment, but I've heard that players made since last year are required to have those decoders built in.

When I use the option for subtitles or CC they were blanked out. That tells me they did not put it in.

Closed-captioning should be controlled by your TV's display options rather than your DVD player.

Yes, my TV has it but it's the same on the computer (VLC).

I have found that VLC can show both subtitles and closed captions (but not at the same time),
so that's a handy way to check.

Over the years I have found many titles claiming to have subtitles or closed captioning where there were neither. Not to mention incorrect claims of extras, widescreen or anamorphic.

I think it's just carelessness or mis-communication on the part of the package designers.

Lately, I have come across titles that have subtitles, even though they aren't listed. That's nice for a change.