It would be very unusual for you not to be able to get copies of your notes, or at least your original balance, from a student loan lender, and not to be able to get an accounting of the principal, interest and payments. Typically, lenders will let you create an online account that you can use to check the balance due on your loan and your payment history. Granted, you appear to be in default and perhaps have been in default for years, which may complicate your access to any online accounting -- but we can't investigate that for you.

If you're at the point where you've been sued and now owe a judgment for the debt balance, then you can verify the amount of the judgment with the court that issued the judgment. You would have had the opportunity to seek information about and to dispute the loan principal and balances claimed when you were sued.