We are currently migrating servers (2005 to 2008) and our host backed up the SQL database and transferred it to the new server.
I have transferred the website files and changed the IP address in the connection string and the global.asa file.
So technically speaking we have a mirror image on the new server, but when I try to launch a page that connects to the SQL I get the following error:
SQL_Server_does_not_exist_or_access_denied.
The error message in this case is very likely correct. First, verify that the network path from you to the new server works and you can connect with the specified userid/pwd.
1) Open Management Studio and attempt to connect to the SQL Server instance by ip address. (By the way, you will probably need to use a SQL Server userid/pwd if you aren't already since you're on an Internet host and there is very likely no AD context for Windows auth.)
2) If you can indeed connect to the instance and your database using Management Studio then you've probably missed a connection string somewhere. Try to maintain only 1 location for said connection string, usually in a config file. Examine the error line reported in detail to discover which connectionstring is being used and to verify that it reflects the new server ip.