This is the 3399th most frequent Russian word.
потеряла
"Lost" (feminine, past tense).
The word 'потеряла' here is used to indicate that 'she' misplaced or can no longer find her house keys.
Она потеряла ключи от дома.
She lost the keys to the house.
In this instance, 'потеряла' is figuratively used to express that 'she' did not utilize her time effectively or wisely.
Он сказал, что она потеряла время.
He said that she wasted time.
Here, 'потеряла' signifies that 'Mary' no longer possesses an emotional or intellectual engagement or attraction to continue studying music.