One of the solution could be:

close data all

lcdbc="DBC_file_name.dbc"
if not file(lcdbc) && add other conditions as needed
.....
else
on error wait wind "Database "+lcdbc+" is corrupted."
use DBC_file_name.DBC
use
on error
endif

>Hi,
>
>I have a customer whose .dbc file has become corrupted. Is there any way of validating it from within the program?
>
>The idea being...
>Start program
>Check that database is valid.
>If valid, copy database to backup.
>Else warn user that database is invalid.
>
>
>Regards
>Doug Johnston