SQL or Structured Query Language Server is a Relational Database Management System (RDBMS). It is designed to compete enterprise environment against My SQL and Oracle Database (DB). It runs on Transact -SQL (T-SQL), a combination of Sybase and Microsoft’s programming extensions. Owing to T-SQL, the standard SQL is supplemented with several features including error handling, declared variables, row processing, exception and transaction control. Apart from T-SQL, its own implementation, SQL Server contains SSMS (Server Management Studio/ Enterprise Manager), which supports 64 and 32-bit environments and is a main interface tool. Similar to all RDMS, it supports ANSI SQL, which is the standard SQL language. It operates in any of two authentication modes: Mixed Mode or Windows Authentication Mode (default) Providing password protection to the SQL Server proves your identity to the system, besides it provides privacy from the person who is not allowed to access the information. It works as an individual identifier and should be known to exactly the same person. It should be stored in a safe manner and regularly changed. While you are installing it, login the server with Windows Authentication, if you select mixed mode authentication, login it with SQL Server Authentication. In Windows Authentication, user can only assign the password after complete installation. However it is not the case with Server Authentication, where the user can assign password during installation. Client connections arbitrates the security mode choice. If your incoming clients do not support trusted connections, it is advised that you select Mixed Mode. If all your clients support trusted connections then go for the default mode or Windows Authentication Mode. Having a SA or System Administrator password is the must. It authenticates your identity to the system. By applying SA Password, the administrator has complete access over the user files. If you have forgotten your Structured Query Language Server SA password and if the windows account tools that you don’t have authority to change it, try these methods to reset your password: Method 1 : Try to run the following commands on the command prompt (assuming your Server name is SQLEXPRESS): osql -E -S .SQLEXPRESS exec sp_password @new=’changeme’, @loginame=’sa’ go alter login sa enable go exit After running these steps over command prompt, try login in with the new user name sa and password changeme Method 2 : If you have other SQL Server Login, which is a part of sysadmin role, try login in from that account and reset the password. Method 3 : If you have other Windows Login, try to login using that. Start SQL in Single User mode.