Why are my questions' words gray in yahoo, and why can't I click on them?

Grayed out questions in your list mean that they have been deleted for whatever reason, but they remain in your list - just not clickable. It can have several reasons why questions get deleted, in your case it most likely happened because you didn't get any answers during the answering period of 7 days, but it also happens when the BA for a resolved question gets reported for violating YA rules - if there are no other answers, the question itself will also get deleted.

The "gray" is your warning that you won't be able to see them when you click on them. Usually they will disappear after a while. Sometimes they were caught in a "filter" by Yahoo. There is a filter that puts asterisks in the place of a swear word. Other filters are for spam. Others were reported by someone who saw the question. If the reporter was wrong, it will be reinstated and not gray.