Resync MySQl Database

At the master:

RESET MASTER;
FLUSH TABLES WITH READ LOCK;
SHOW MASTER STATUS;

And copy the values of the result of the last command somewhere.

Wihtout closing the connection to the client (because it would release the read lock) issue the command to get a dump of the master.

mysqldump -uroot -p --all-databases > /a/path/mysqldump.sql

Now you can release the lock, even if the dump hasn't end. To do it perform the following command in the mysql client.

UNLOCK TABLES;

Now copy the dump file to the slave using scp or your preferred tool.

At the slave

Open a connection to mysql and type

STOP SLAVE;

Load master's data dump with this console command.

mysql -uroot -p < mysqldump.sql

Sync slave and master logs

RESET SLAVE;
CHANGE MASTER TO MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=98;

Where the values of the above fields are the ones you copied before.

Finally type

START SLAVE;

And to check that everything is working again, if you type

SHOW SLAVE STATUS;

You should see

Slave_IO_Running: Yes
Slave_SQL_Running: Yes