Life is a mystery = 人生は神秘　or 人生はミステリー

You didn't appreciate it =　感謝しなかった

Someone took my place (Not 場所) =　誰かが私の席を取った
(It depends on the situation. 'Place' can be seat, position, or place in somebody's heart etc...)

You broke my heart = あなたが私(の心)を傷つけた。

in Osaka-ben do you say じゃへん as in 食べへん?

we don't use 'じゃへん', i guess.
but we use 'じゃない'　for negative phrase.
for example, 私は日本人じゃない。
but it's not Osaka-ben.

If you have other questions, let me know ;)

Good Luck!