My 16 year old daughter ran away 6 days ago with her 23 year old boyfriend who also happens to be a convicted child molester. She is using a textnow app on a deactivated cell phone she got from one of her friends. I'm desperate to find her.
It appears that TextNow can provide some potentially meaningful details to law enforcement. It is however unlikely they would comply with a request directly from you. Their info page is here: https://supportfree.textnow.com/hc/en-us/articles/204431979-Law-Enforcement-Subpoena-Requests
If you have not yet involved the police (and if you are in USA requested an Amber Alert to be issued) this would most definitely be the time to do so. You'll need the authorities to request this information anyway, and they will have their own ways of trying to locate them which may be far faster than getting info from TextNow.