As I recall, when Day left Hollywood after doing her TV series, she didn't consider herself retired from acting and still read scripts and considered offers that came her way. But she didn't like the stuff she was being offered. She said it wasn't until she met with Albert Brooks and read his script of Mother which she really liked that she realized the script she had been waiting for had arrived but she had lost all interest in acting. So that chapter in her life was closed once and for all. Debbie Reynolds ended up playing the part.