To retrieve the plesk admin password please do the following:
In Plesk 11.5 and previous versions the file is located in the
%plesk_bin%
folder- In Plesk 12 this utility was moved to the
%plesk_dir%\admin\bin\
folder
1. Open a command prompt
2. Type "cd %plesk_bin%" (without the quotes) and press Enter (If using Plesk 11 or lower)
2a. Type "cd %plesk_dir%\admin\bin\" (without the quotes) and press Enter (If using Plesk 12 or above)
3. Type "plesksrvclient -get -nogui | more" (without the quotes) and press Enter
4. Your password will now be printed in the Command Prompt Window.