YOU SAID:

I can never do anything good.

INTO JAPANESE

私は何か良いことはできません。

BACK INTO ENGLISH

I can not do anything good.

INTO JAPANESE

私は何か良いを行うことはできません。

BACK INTO ENGLISH

I do something good can not do.

INTO JAPANESE

だが俺には出来ない...

BACK INTO ENGLISH

I can not do it...

INTO JAPANESE

だが俺には出来ない...

BACK INTO ENGLISH

I can not do it...