Fixing AutoNumbers when Access assigns negatives or duplicates

I ran across this post from Allen Browne on resolving problems with autonumbers. It seems like a useful post to keep handy for when I need it someday.

In Access 2000 and later, an AutoNumber field may begin assigning extreme values, negatives, and even duplicates. The attempt to assign a duplicate fails if the field is primary key, so it may not be possible to save new records in an affected table.