I have bought an ASA 5520

I was working on it and I was tested to it.I do not know what I have done but

When I write dir command it show :

ciscoasa# dir

Directory of disk0:/

9 -rw- 1248 10:45:10 Dec 19 2007 startup-config

255426560 bytes total (255361024 bytes free)

I can not find ather files there like cdisk.bin , asdmfile.bin or first-backup.

does anybody know what can I do to find them.