Did you have any kind of income at all?
Thanks for the additional information. I apologize for not getting back sooner, but I got called away to a conference call.
If your savings produced interest, you would file a return to report interest. Likely you would owe no tax.
I understand the need for permanent residents (green card holders) to show continuity for compliance with income tax filing;
So what you can do is file an information return, and include zero income; or if you have interest, no matter how little, report that.