When faced with any creditor: "call them!"
“Your present financial situation is what it is,” and, believe me, you are not the first. Therefore, be the one to contact your creditor to begin to negotiate. Don’t leave them out there in the dark, wondering what is going on. That’s not fair. They have lots of ways to work with you, as long as you first approach them “in good faith.™” (After all, they want their money back, if they can get it, and the possibility always exists that they can’t.)
You most certainly are are not(!) the very first party to have entered into a credit agreement, “and then, something changed.” Creditors deal with thousands of identical cases every day. It’s a “business risk” that they take. Don’t make them send you letters: face it head-on. “These things, too, shall pass.”