In phpMyAdmin or MySQL shell
UPDATE UMBRACOUSER
SET userdisabled=0, userLogin='admin',
userPassword='bnWxWyFdCueCcKrqniYK9iAS+7E='
WHERE id=0;
This query resets your password to default
.
In SQL Server Management Studio
UPDATE [databasename].[dbo].[umbracoUser]
set userdisabled=0, userLogin='admin', userPassword='bnWxWyFdCueCcKrqniYK9iAS+7E='
where id=0
Umbraco admin reset .NET project
Richard Soeteman created an Umbraco Admin reset project which sets the admin username to Admin and sets the password to Admin1234!. You can find the project here.
More password resets: WordPress
Oh my! Lost your WordPress password?