Your private student loans (unlike your federal loans) were probably made with the help of a cosigner. The cosigner's current financial state will have a significant impace on your lender/servicer's willingness to deal. So, if your cosigner and you are both struggling, this is the time to seek modification!
Start early, somewhere between 30 and 120 days into delinquency, and don't give up. These private student loans CAN be discharged in bankruptcy if you qualify and can prove undue hardship. Attempting to renegotiate will also show that you were making a "good faith" effort to pay - which is important should you reach that stage.
Lender/servicers are under pressure by the Consumer Financial Protection Bureau - a Government agency - to provide mechanisms for relief for private student loan borrowers, so consider seeking help and/or filing a complaint with the CFPB if you feel you're being treated unfairly.
Lastly, there are millions of dollars of private student loans being collected by debt collectors. Some are using illegal tactics like threatening to sue on a debt that's too old, reporting an old debt on your credit report as new, using a robo-dialer to repeatedly call you without your consent, and trying to get you to agree to new terms in order to refresh the debt. If any of these are happening to you, get in touch with me immediately!