This morning my AmazingCharts.xml disappeared too! I thought it was because someone deleted it (still probable) but maybe it wasn't just us. We were not upgrading or anything though. In any case here is what I did. I recreated the xml file by making a file called AmazingCharts.xml and put this text in it (replacing C:\Sample\AmazingCharts.mdf with your path to this file)
Code
<?xml version="1.0" encoding="utf-8"?>
<AmazingCharts>
  <Settings>
    <LocalDbPath>C:\Sample\AmazingCharts.mdf</LocalDbPath>
    <SqlPortNumber>61067</SqlPortNumber>
  </Settings>
</AmazingCharts>

Next you will need to open Amazing Charts.exe on the "main" computer and it should automatically reconnect the xml file with the SQL server.

Paul Paschall
IT