Please can you explain in more detail what you mean when you say it has "dissappeared"?
Do you simply mean that it doesn't show up in the logon screen? If so then you should attempt to
ADD AN EXISTING DATABASE - you definitely should NOT be restoring from a backup as that will re-create the database all over again.
ClinicOffice
NEVER (I repeat
NEVER!) deletes a database unless the user absoutely chooses to do this and confirms it several times. Hence, the chances are that your database is already there, but you just need to tell ClinicOffice where it is.
Please see this FAQ for more information :-
viewtopic.php?f=3&t=215
As regards linking the two up again, please see this FAQ :-
viewtopic.php?f=5&t=9