sallyb, the clearing of the data may not have happened at conversion but possibly at a fiscal year end depending if you have done one since June. It has happened to many of us if we hit the accept/enter/process/start/yes button way to quick, like before the screen has been fully read and understood.
I would suggest that you try another conversion from your back up file which you have from immediately prior to conversion. Use a different file name so as not to overwrite your current file. If this works and the details are still there then you at least have access to the data.
Depending on the volumn of input you may wish to re-do the entries since conversion but it may not be necessary if the second set of data is convenient for you.
You can check if your database has been corrupted by going to the Maintenance menu from the home screen and verify data. If there is corruption this will show which module the corruption is in and then you know where to start to find it. The solution will vary depending on the situation.
HTH
Clyde