Don't try to go through the US. It's not worth the hassle.
The best solution is to get someone to send you the PR card through the mail. This exact thing happened to a friend of mine and we had to get a lock smith to open her apartment door, then found her PR card and mailed it to her in Costa Rica.
If you don't have the possibility of having your PR card mailed to you then apply for a permanent resident travel document as soon as possible. I'm assuming you're in Brazil. I don't think the processing timelines for the embassy there would be too long. Just apply for it as soon and you can and hope for the best.
