what can i do when my iphone 3gs is in error 40? because they did not complete the restoration or recovery mode.

Plug your device into a PC or a MAC then iTunes should detect your device is in recovery mode and release you from recovery mode.

ITUNES will automatically pick it up and a pop up box will probally say that your IPHONE is in recovery mode would you like to restore?

3. Click the restore tab.

Note - If ITUNES if out of date, this will not work.

Note - Do not do this over WIFI

Note - Do not interrupt the restore

Note - If you did not make a previous back up, your IPHONE will restore back to the factroy settings.

This is the real reason: http://support.apple.com/kb/TS3694#error40

Try again, this time disabling your antivirus and firewall first.