I think it nobody knows about 'wrong' act, it is okay.
The definition of 'wrong' is 'not fitting or suitable; inappropriate or improper'. If nobody noticed that something happened, it means that the act you did didn't affect others. It isn't improper or not suitable. The 'wrong' might give bad effect to others if it is really bad. But nobody notice, get any effect. Therefore it is fine. The 'wrong' act might be bad to someone but on the other hand, it might help some other people. For example, the Robin Hood in ancient Korea, although it is just a story, he stool the riches' money and food and gave them to poor people. In the story, on the side of rich people, steeling is very bad and wrong act. However, on the poor people's side, it is a good act because the Robin Hood gave back their stolen money and food. I think if the wrong act doesn't affect in bad way and nobody knows, it is not wrong at all.

CORRECT:

I think that nobody knows about 'wrong' act. It is okay.
The definition of 'wrong' is 'not fitting or suitable; inappropriate or improper'. If nobody noticed that something happened, it means that the act you did didn't affect others. It isn't improper or not suitable. The 'wrong' might give bad effect to others if it is really bad. But nobody notices and gets affected. Therefore, it is fine. The 'wrong' act might be bad to someone but on the other hand, it might help some other people. For example, the Robin Hood in ancient Korea. Although it is just a story, he stole the riches' money and food and gave them to poor people. In the story, on the side of rich people, stealing is very bad and is a wrong act. However, on the poor people's side, it is a good act because Robin Hood gave back their stolen money and food. I think if the wrong act doesn't affect in bad way and nobody knows, it is not wrong at all.

>>Be mindful of the correct spelling of a word. 'nobody' is a singular pronoun, thus it takes singular verb. A comma should be placed after the conjunction 'therefore'. 'stole' is the past tense of the verb 'steal' which means to secretly take something that belongs to someone else.