If you want to be really technical, it would be “That’s a question I ask myself every day.”
The single word “everyday” is an adjective. It can be used to mean “common” or “normal”.
To say “It’s an everyday occurrence” means that it happens every day.
This might be pedantic of me to point out, but it’s one of those little things that I see quite often.
"one" in this sentence isn't a number - it's actually a pronoun, standing in for the thing that you're looking for - if someone is handing around doughnuts, and you don't get one, then the "one" in "where's my one?" is referring to a doughnut.
In the Irish sentence, ceann is a pronoun that plays the same role that "one" plays in the English sentence.