650 years ago, the place I live was inhabited mostly by the Ojibwe (a Native American people), so I suppose I'd try to find some of them and try to convince them to not kill me and let me stick around long enough to learn their language. Then I could teach them some of my knowledge. Maybe by the time the Europeans come along they'll be a bit more prepared.
If I can't find anyone, I don't like my chances of surviving for any significant amount of time. Maybe I could make it a few weeks foraging for food and fishing or something, but realistically I'll probably end up starving.
Well... Did they suck your balls?