i don't like apple,or banana and pear.

把and去掉，把or放在and的位置就对了

I don't like apple, nor banana and pear.

I don't like apple, banana or pear.

i like neither apple nor banana and pear

I don't like apple or banana or pear.
其实你这种说法在语法上也是对的，or 也有“ 和”的意思，但是是用在否定句中，and 作为“和”的意思可以用在肯定句和否定句中。就是说在否定句中作为“和”的意思他们两个是通用的。

应该是I don't like apple,banana or pear.

i dont like apple,banana and pear