Ugh, this broke my heart. I wanted to badly for her to tell you what happened, to somehow make it better.
My daughter is 4.5, and she’s always singing. She went on stage to be in a talent show this summer, with her little ukelele. She’d been planning for it all year, after seeing the previous year’s talent show. She practiced and practiced for months, and then she got stage fright. Just completely froze up there. I was so afraid she’d be scared off of it forever, but after we regrouped and cuddled in the bathroom, she told me she wants to try again next year, but not by herself next time.
Everything you wrote makes it so clear what a great parenting job you’re doing, and I bet your daughter will sing again when she’s ready!