If you will be stuck with having to pay back student loan debt, you may have an out. Many times, these loans have been purchased, re-purchased, and generally passed around through various debt servicers. Someone along the way may have dropped the ball, i.e. the chain of ownership of the debt. Regardless, sending a debt validation letter will provide you more information about whom the original owner was, the amount claimed that you owe, who currently owns the debt, etc.
Here is a site that walks you through creating a debt validation letter for a fee:
https://www.solosuit.com/posts/make-debt-validation-letter-guide
They even provide a template if you don’t want to pay:
https://dgkb7ybxr0cqd.cloudfront.net/Debt-Validation-Letter-template.pdf
What to do if the debt collector cannot validate your debt but is still demanding you pay:
https://consumer.ftc.gov/articles/debt-collection-faqs#report