SQL 401: cannot open database

Detach you database. Overwrite the mdf and ldf files you've restored from your backup with your files from the D: drive. Reattach the database.
There is no guarantee that this will work or if it works, that your database is in a state where you can continue to work with.
If that doesn't work then there is an option to try to restore database using SQL Server Recovery Toolbox. It is a powerful tool for data recovery. They have a demo version. So you can check it works in your situation or not.
http://www.oemailrecovery.com/sql_repair.html

You can find more information here:
http://www.filerepairforum.com/forum/microsoft/microsoft-aa/sql-server/569-i-have-a-problem-how-do-i-fix-a-corrupted-database-file

Open your SQL Server Management Studio console. This application shortcut is available in the SQL Server directory in the Windows Start button.
· Enter the system administrator user name and password. SQL Server's administrator user name is "sa." This account is required for privileges to restore the database. If your restoring on a host provider server, use the administrator user name and password they supplied for your account.
·Right-click your database name and select "Attach." In the new window that opens, click the "Add" button to open a dialog box.
·Select your MDF file and press the "Ok" button. It may take several minutes to restore the database if it is a large file. Once the process is finished, browse your tables to verify the data. The database is now restored.
If nothing helped try to use:SQL Server Fix Toolbox
http://www.fixsqldatabase.com/

There is one SQL password recovery tool, SQL Password Genius, which would help you to successfully change SQL Server 2005/2008/2012 user password instantly, especially when you couldn't think of other ways for it.

1. Open SQL Server Configuration Management and stop SQL Server Services.

2. Install SQL Password Genius full version and run it on computer.

3. Click "Open File" button to import master.mdf database file into this recovery tool.

4. Select user in list and click "Reset" button.
Instantly, new user password would be available for SQL Server logon after you type new password for user.

Now, SQL Server user password has been changed and you can login into SAL server now. But please remember to restart SQL Server Services before you access to SQL Server with user password.

How to Reset SA Password in Sql Server Visit this link to get more details. http://electronicshelponline.blogspot.com/

When SA password for SQL Server logon forgot, please take SQL Password Genius to install it on computer.

Step 1: Run SQL Password Genius full version and browse Master.mdf file to import into it.

Step 2: Select SA user and click "Reset" button.
After master database file imported into SQL Password Genius, you would see all user in list. SA password is unknown. Select SA account and click "Reset" button.

A new window would pop up, type new password for SA account in it. And click "OK". Instantly, SA password is changed successfully. SA password lists in software screen.

Step 3: Close SQL Password Genius and restart SQL Server Services.

SQL Server services influence SQL password reset on computer. So we stop it before using SQL Password Genius. Now, when you finish SQL SA password reset, restart SQL Server Services to run SQL Server with SA account.

How to Reset SA and Other User Passwords for SQL Server

According to Wikipedia:-

Access Project .adp
Access Blank Project Template .adn
Access Database (2007) .accdb
Access Database Runtime (2007) .accdr
Access Database Template (2007) .accdt
Access Database (2003 and earlier) .mdb
Access Database, used for addins (2,95,97), previously used for workgroups (2). .mda
Access Database Template (2003 and earlier) .mdt
Access Workgroup, database for user-level security. .mdw
Access (SQL Server) detached database (2000) .mdf
Protected Access Database, with compiled VBA (2003 and earlier) .mde
Protected Access Database, with compiled VBA (2007) .accde
Windows Shortcut: Access Macro .mam
Windows Shortcut: Access Query .maq
Windows Shortcut: Access Report .mar
Windows Shortcut: Access Table .mat
Windows Shortcut: Access Form .maf

A trigger is a special kind of stored procedure that automatically executes when an event occurs in the database server. A trigger is really an event handler. SQL Server allows users to create triggers (event handlers) for 3 types of events:

• DML Event - Occurs when a DML (Data Manipulation Language) statement: INSERT, UPDATE or DELETE, is executed.
• DDL Event - Occurs when a DDL (Data Definition Language) statement: CREATE, ALTER, or DROP, is executed.
• Logon Event - Occurs when a user logins to the Server.

There are 3 different types of triggers (event handlers) based on the types of events they are triggered by:

• DML Trigger - Executes in response to a DML event.
• DDL Trigger - Executes in response to a DDL event.
• Logon Trigger - Executes in response to a logon event.

An easy way to transfer objects (tables, user defined functions, stored procedures, etc.) is to use Enterprise Manager's "Generate SQL" feature. Use this process at your own risk. Doing it wrong could mess up your existing database.

1. In Enterprise Manager, right-click on the old database and choose "All Tasks" then "Generate SQL Script".
2. In the dialog that comes up, click "Show All" then select the checkboxes for "all stored procedures" and "all user defined functions". (You might also want to check some other boxes, depending on your exact situation.)
3. Click the "generate" button and save the script that it creates.
4. Run the script in the NEW database.

If you run the script in your OLD database, it may destroy your objects, and that would be very bad. Make sure you run the script in your NEW database. (While we're on this subject, it's a good time to mention that you should back up your database before you start this process, and you should make changes to a test system before migrating it to production.)

That should move your stored procedures and user defined functions over.

You can use a similar process to move tables, views, users, and other objects over as well.