why did my back up alert stop working?

What is your question?

My Tundra used to tell me in a females voice how close I was to something while backing up. It would yell crash if I was too close. It did work once a few months ago but has not worked for almost a year.

What makes this problem better or worse?

Nothing

How long has your 2005 Toyota Tundra had this problem?

Almost a year