Plesk Controlpanel has several tools to retrieve the ‘admin’ password to gain entrance to the Controlpanel. Up to version 10.2 these were just unencrypted text files (say what?) on the server. Since 10.2 you need to use a command to retrieve them in plain text (sounds better, doesn’t it?).
Linux
For all versions lower than 10.2, just use the following at a shell:
# cat /etc/psa/.psa.shadow
For all versions higher than 10.2, use this:
# /usr/local/psa/bin/admin --show-password
In both cases, you’ll see the admin password in plain text.
Windows
On Windows, you can use one of the following.
> "%plesk_bin%\plesksrvclient" -get > "%plesk_bin%\plesksrvclient" -get -nogui