To backup your mysql database type the following.
mysqldump -u username -ppassword database_name > dump.sql
make sure not to leave a space between the -p and the password, otherwise mysql will prompt you for a password and will assume that your password is the database name.
the entire database will be backed up into the dump.sql file
then to restore the database type the following
'mysql -u username -ppassword database_name < dump.sql'