Hi Somebody92,
Thanks for visiting the Apple Support Communities.
First, make sure you are sending the message to the contact's Apple ID. The iPod touch on its own can receive iMessages sent to the user's Apple ID, so it's possible sending it to their phone number will not deliver to their iPod touch.
We can also suggest going through the troubleshooting steps outlined in the Apple Support article If you can't send or receive messages on your iPhone or iPad - Apple Support, which targets issues sending and receiving messages while using an iPhone.
Should you still need help after that, please get in touch with Apple Support directly. They will have access to the tools and resources needed to further investigate the issue. You can do that here: Contact - Official Apple Support.
Have a wonderful day.