>How can i know if there is a diskette in the drive A:?
>Can i do that using an Api?
>Can i do that with Vfox?
>Thanks for any advice

Make it easy:
nFile=fcreate("test.txt")
=flose(nFile)
lErrflag=.f.
on error lErrflag=.t.
copy file test.txt to a:\test.txt
on error
if lErrflag=.t.
=messagebox("Insert Disk into A")
return
endif
delete file a:\test.txt
*** and do whatever you want...