I believe this is a serious question so I'll give you a serious answer.
It is not all that uncommon for a person to be born missing the pectoralis major and/or minor on one side. The only true cosmetic remedy for symmetry would be an implant. I have seen it done. It came out very well. The result was a nice big rounded pec like the other side. Very effective. A plastic surgeon is where i would start.
This will not produce power or atrength...'cos there is no muscle...right?
is it that bad bro? i mean lots of people have muscles that arent exactly the same size. my right leg is slightly bigger than the left. i just work my left leg harder.