Learn English – Is there one word that means the inability to remember an event

Is there one word that by itself means the inability to recall when something happened (or anything, for that matter)?

For example, if I am asked to respond to the question, "What date did your child lose her first tooth?" and I can't remember and want to respond to the question with only one word, is there a word that fills the bill? The questioner will understand that I cannot answer because I can't remember?

The only word I can think of is 'forgot.' I'd like to know if there are others.

I am not looking for a psychology term like repressed-memory, or anything else pop-science like that, but merely one word that means I can't recall.