Hi, Leesa_xo.
I'm glad you decided to reach out on Apple Support Communities today. It sounds like you were taking advantage of the free trial offered with Apple Music, and you didn’t realize that canceling it would end your subscription immediately. I understand that you were eager to experience Apple Music.
With a free trial, you can cancel any time, but you won’t have access to the service until the end of the trial period like you do when you’ve paid a subscription fee. It terminates immediately.
This is outlined here:
Subscribe to Apple Music on iPhone
New subscribers can start a trial and cancel at any time. If you end your Apple Music subscription, you can no longer stream Apple Music songs or play Apple Music songs you downloaded.
There may not be anything you can do to get your free trial back again, but I would contact Apple Support to be certain.
Best Regards.