Help me Please

MY DA's MYSQL is 4.1, but i need to downgrade 4.0,
today i start to downgrade my mysql,
i link to mysql database....he show me :

Error connecting to MySQL: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)


Help me Please
What can i do now???
somebody can step by step teach me???
thank you very much~~

register new user for help lool

just try rpm -Uvh --force to go back 4.0 or to update 4.1