To add Builtin\Administrator account in sql server login

Recently I got a problem where Builtin\Administrators  Account was deleted  . How can we recreate it?

Here is a solution for this
Run this proc

EXEC sp_grantlogin 'BUILTIN\Administrators'   to recreate it
Then give it sysadmin rights on the server.

Or in Management Studio
go to
Secuirty -> Logins -> right click to new login

Type 'BUILTIN\Administrators'  as login name , choose widows Authentication
In Server Roles , give its a right of sysadming

By default this account all adminstrator in the administrators account.