My answer however i need help with it as you can see i haven't answered the question fully-her attitude was always positive but can be undone quickly by her disturbing thoughts-

The question says Explain, using your own words, what Christopher tells you about his mother’s character
in lines 22–26
and here's the lines of 22-26
I began to remember one
occasion when my mother and I had indeed been standing together up on that
attic floor, for all I know playing this game of ours, when she suddenly stopped and
became very still.
My first thought was that I was about to be scolded, perhaps for something I had just
said which had displeased her. It was not even unheard of for my mother to switch
moods abruptly in the midst of a good-natured exchange and scold me for some
suddenly remembered misdemeanour committed earlier in the day

This is your answer.

"her attitude was always positive but can be undone quickly by her disturbing thoughts- "

If you added appropriate capitalization and punctuation, your answer would be good.