I faced the same problem after executing the following command in mysql
UPDATE mysql.user SET Password=PASSWORD('blablabla') WHERE User='root'; FLUSH PRIVILEGES;
what I did:
open cmd
type
cd c:\xampp\mysql\bin mysql.exe -u root --password
after that mysql will prompt u
Enter password:blablabla
once youre in mysql, type
UPDATE mysql.user SET Password=PASSWORD('') WHERE User='root'; FLUSH PRIVILEGES;
Note: this time the password is left empty...
make sure in your config.inc.php the following is set
$cfg['Servers'][$i]['password'] = '';
$cfg['Servers'][$i]['AllowNoPasswordRoot'] = true;
after that I can see my phpmyadmin...