Firstly, make sure all the point values are properly set in admin/points. This includes, but it is not limited, to making sure you don't have a value of 0 for the Multiply all points setting. Then make sure to click the Save and recalculate button there or the Recalculate user points in the admin/stats section.
Anyway, something has happened that created this issue. It is usually some plugin or theme fault. If you don't remove the cause of issues they will appear again.
