#1045 - Access denied for user 'root'@'localhost' (using password: YES)

I first changed the root password running mysql at a prompt with

mysql -u root -p

Update password:

UPDATE mysql.user SET Password=PASSWORD('MyNewPass') WHERE User='root';

Edited line in the file config.inc.php with the new root password:

$cfg['Servers'][$i]['password'] = 'MyNewPass'

Stop and re-start mysql service (in Windows: mysql_stop.bat/mysql_start.bat)

and got phpMyAdmin to work!

EDIT 2017: for MySQL≥5.7 use authentication_string in place of Password (see this answer):

UPDATE mysql.user SET authentication_string=PASSWORD('MyNewPass') WHERE User='root';

The problem was I have 2 instances of Mysql installed and I didn't know the password for both instances.Just check if port 80 is used by any of the programs. This is what I did

1.Quit Skype because it was using port 80.(Please check if port 80 is used by any other program).

2.Search for Mysql services in task manager and stop it.

3.Now delete all the related mysql files.Make sure you delete all the files.

4.Reinstall

Well, there are many solutions already given above. If there are none of them works, maybe you should just try to reset your password again to 'root' as described here, and then reopen http://localhost/phpMyAdmin/ in other browser. At least this solution works for me.