Código: Seleccionar todo
UPDATE phpbb_users SET username = replace(username,'','');
UPDATE phpbb_users SET username = replace(username,'á','á');
UPDATE phpbb_users SET username = replace(username,'é','é');
UPDATE phpbb_users SET username = replace(username,'í','í');
UPDATE phpbb_users SET username = replace(username,'ó','ó');
UPDATE phpbb_users SET username = replace(username,'ú','ú');
UPDATE phpbb_users SET username = replace(username,'ñ','ñ');
UPDATE phpbb_users SET username = replace(username,'¿','¿');
UPDATE phpbb_users SET username = replace(username,'º','ª');
UPDATE phpbb_users SET username = replace(username,'Á','Á');
UPDATE phpbb_users SET username = replace(username,'É','É');
UPDATE phpbb_users SET username = replace(username,'Ó','Ó');
UPDATE phpbb_users SET username = replace(username,'íš','Ú');
UPDATE phpbb_users SET username = replace(username,'¡','¡');
UPDATE phpbb_users SET username = replace(username,'Ñ','Ñ');
UPDATE phpbb_users SET username = replace(username,'À','À');
UPDATE phpbb_users SET username = replace(username,'íˆ','È');
UPDATE phpbb_users SET username = replace(username,'È','è');
UPDATE phpbb_users SET username = replace(username,'í’','Ò');
UPDATE phpbb_users SET username = replace(username,'í²','ò');
UPDATE phpbb_users SET username = replace(username,'í','í');
UPDATE phpbb_users SET username_clean = replace(username_clean,'','');
UPDATE phpbb_users SET username_clean = replace(username_clean,'á','á');
UPDATE phpbb_users SET username_clean = replace(username_clean,'é','é');
UPDATE phpbb_users SET username_clean = replace(username_clean,'í','í');
UPDATE phpbb_users SET username_clean = replace(username_clean,'ó','ó');
UPDATE phpbb_users SET username_clean = replace(username_clean,'ú','ú');
UPDATE phpbb_users SET username_clean = replace(username_clean,'ñ','ñ');
UPDATE phpbb_users SET username_clean = replace(username_clean,'¿','¿');
UPDATE phpbb_users SET username_clean = replace(username_clean,'Á','Á');
UPDATE phpbb_users SET username_clean = replace(username_clean,'íƒâ‚¬','Á');
UPDATE phpbb_users SET username_clean = replace(username_clean,'‰','É');
UPDATE phpbb_users SET username_clean = replace(username_clean,'Ó','Ó');
UPDATE phpbb_users SET username_clean = replace(username_clean,'íš','Ú');
UPDATE phpbb_users SET username_clean = replace(username_clean,'¡','¡');
UPDATE phpbb_users SET username_clean = replace(username_clean,'Ñ','Ñ');
UPDATE phpbb_users SET username_clean = replace(username_clean,'À','À');
UPDATE phpbb_users SET username_clean = replace(username_clean,'íˆ','È');
UPDATE phpbb_users SET username_clean = replace(username_clean,'È','è');
UPDATE phpbb_users SET username_clean = replace(username_clean,'í’','Ò');
UPDATE phpbb_users SET username_clean = replace(username_clean,'í²','ò');
UPDATE phpbb_users SET username_clean = replace(username_clean,'í','í');
Pero si no es así mira qué carácter aparece en tu base de datos para tu nombre, y cambia ese por é en cualquiera de esas sentencias que acabo de pasarte.