Confused by SQL Server Express when create a new database

Question

I am an administrator of of my own machine, I have SQL Server Express installed. But when I tried to create a new database I got this error

Create Database permission denied in database 'master'

I figured I was missing 'sysadmin' role for my login. When I tried to add my self as 'sysadmin' I got another error

User does not have permission to perform this action

I am the administrator of this machine, why cannot I have permission to create a new database in this SQL Server Express instance?

Thanks

Answer 1

This post may be helpful as well. It points to a script that allows you to add yourself to sysadmin role (provided that you are a local Windows admin).

Update As the link to the actual script is gone, refer to the StackExchange answer on how to take ownership of a SQL Server.