Ok so the ETH I had tuned into the same ETH but the new one which use POW? The old one has no name and there are nothing to find these coins? Sorry about my confusion.
You are using MEW as you said. So, you are okay and don't have to do anything. It is for people who use software wallet and they have update with the newest version. There is nothing to worry if someone wrongly send ETH from older version. The coins are safe.