What does it mean to me if the US declares bankruptcy?

A nation can't really declare bankruptcy. Historically when a debtor nation has defaulted to that degree it has been met with blockades, embargoes, or war. While it is possible a debt could be settled with an exchange of land/other physical accents most of the time that hasn't happened. As such things tend to hassle the creditor, or the debtor just falls back on their army. Typically after a nation has defaulted and usually shortly after affairs are settled with the creditor there is a radical regime change (as in revolution)