第一句：That's all right.
A: I'm sorry I forgot to bring the key of my room.
B: That's all right.
第二句：It can't be helped.
A: I'm sorry I'm late. The train was delayed.
B: That's all right. It can't be helped.
Don't worry about it. 别担心，不必介意。
It's nothing. 没关系。
There is no need to apologize. 没必要道歉。
It's not your fault. 不是你的错。