I installed the SQL server Express 2008 R2 and then SQL Server Management Studio 2008 R2 . But during the installation, I could not choose the both SQL and windows authentication mode and an error accrued so I did that just with windows authentication mode. 
Now, I want to change the windows authentication mode account to the SQL authentication mode but it shows me an error which is you do not have permission (Although I am the administrator in windows), what can I do?
Following steps are the steps that I went but I got an error:
Server properties >> security >> choose the option of SQL Server and Windows Authentication mode 
and the error that I got is attached(access is denied)  
Can you please help me?

You can change the setting after you gain admin rights to your SQL Server. You don't admin rights automatically, you have to explicitly add yourself during the install

Here's a guide on how to (re)gain those rights:

http://v-consult.be/2011/05/26/recover-sa-password-microsoft-sql-server-2008-r2/

You can change the setting after you gain admin rights to your SQL Server. You don't admin rights automatically, you have to explicitly add yourself during the install

Here's a guide on how to (re)gain those rights:

http://v-consult.be/2011/05/26/recover-sa-password-microsoft-sql-server-2008-r2/

• Proposed as answer by Katherine XiongMicrosoft contingent staff, Moderator Friday, May 01, 2015 7:07 AM

 Thanks for your guidance but it couldn't solve my problem. When I want to open the sqlcmd one error occurred that "Server is in single user mode. Only one administrator can connect at this time." 

This computer has two admin one is the IT admin and myself. 

Do you have any suggestion in this situation?

Hi

That means something else is connecting in before you get the opportunity.

- Make sure the SQL Server Agent isn't started. 

- Make sure no application services are connecting (e.g. stop your connecting website, etc).

- Make sure no other automated processes are connecting (e.g. scheduled tasks)

• Proposed as answer by Katherine XiongMicrosoft contingent staff, Moderator Friday, May 08, 2015 3:12 AM
• Marked as answer by Katherine XiongMicrosoft contingent staff, Moderator Monday, May 11, 2015 2:50 AM

Hi

I could create a new SYSADMIN  account by your guidance but unfortunately when I want to connect to the SQL with this new account, the another error accrued.

I really appreciate that if you can help me with this too.  

Hi

see here

https://technet.microsoft.com/en-us/library/ms175496%28v=sql.105%29.aspx

it has typical causes and resolution for this error.

Thank you so much for your answers but I knew that and I checked that named pipes protocol is which is enabled and also  is listed before TCP in the client protocol order. every thing is OK as the following pic but I really don't know what's wrong with that?? I still get previous error?!!

Make sure it's enabled in SQL "Server Network Configuration\Protocols for MSSQLSERVER". The screenshot you included only seems to be the client.

Yes  it is as you can see :(

You can change the mode from registry

regedit-->HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\MSSQLX.MSSQLSERVER\MSSQLServer\loginmode

1=Windows

2=Mixed

You have to restart the instance after the change.

As a test how about disabling named pipes and restarting the instance? See if the error message changes