Can you get deleted Facebook messages from your cell phone provider?

no

No. Your cell phone provider has nothing to do with Facebook. They can’t even recall the sites you’ve been on on your phone.

You can, but most likely they can’t help you. Some providers can’t even block unwanted calls.

Facebook possibly has all your data and all your private messages and comments you made over the months or years. If you ask them nicely, I’m sure they will send you that data. However, getting in touch with the company is another story in itself.