Here is another procedure
1- Stop MSSQL Server Service
2- Copy all system datafiles to a new folder
3- rebuild your master database, at this point you'll get access to SQL Server with sysadmin rights
4- Start MSSQL Server Service
5- attach old master database, the one backed up on step 2, using the name master_old
6- Execute the foloowing procedure on master_old databases
you will get an script with all the logins in the server with the same sid and password ecrypted.
7- Execute The script from step 6.
8- Attach all users databases
9- set the right default database to every single login.
10- set the rights server roles for every single login.
11- detach master_old database
12- stop mssqlserver service and replaces the datafiles for msdb db with the ones backed up in step 2
13- start mssqlserver service
14- check that everything it's ok, and do a full backup, and also store in a secure place the new credentials for sa
Sorry for my poor english and good luck