Is there anything I can do for you? I want to know. (合并成一句)

改为：I want to know if I can do something for you.应用something而不是anything。因为你用的是if引导的宾语从句，用陈述语序。并且希望得到肯定的回答，必须用anything。

iwanttoknowthereissomethingicandoforyou.

可以说 I want to know anything I can do for you?

用if 引导的宾语从句
I don't konw if there is something I can do for you?

I don't konw if there is something I can do for you

I want to know if there is something I can do for you .