More Likely they are now lost forever because they don't support each other network. That's why before sending some altcoins, you need to fully check every crucial thing before sending it off to the network. This is a common mistake among investors and holders, I hope you only sent a small amount of Altcoins. You just need to move on and used that mistake as an experience. Don't worry it's not only you who does such kinds of things, there are many people out there who wrongly sent their coins to another blockchain network.