Sql-server – How to reinstall SQL Server Integration Services I’ve deinstalled from a Production server by mistake

Yes, most likely. This is a short answer, but it sounds like you are really just asking - Can a job on SQL Server 2008 calling an SSIS package built on 2008 connect to a database in SQL Server 2012 and do some work within that database?

SSIS can connect to many OLEDB/ODBC compliant connections. You could, for instance use an SSIS 2008 (or 2005 or 2012) Package to read data from one Oracle database, do some transformations and the write the results of that to another Oracle database, never talking to SQL except the SSIS engine.

So an SSIS package in 2008 should be able to work with a connection to 2012. Some caveats like - if you are using a deprecated command structure in an execute SQL task - it will fail.. Or test it and verify first. But this should work, if you are just asking if - from within the SSIS package can I talk to SQL Server 2012.

As stated in BOL here:

Cross-platform upgrade is not supported. You cannot upgrade a 32-bit instance of SQL Server to native 64-bit using SQL Server Setup. However, you can back up or detach databases from a 32-bit instance of SQL Server, and then restore or attach them to a new instance of SQL Server (64-bit) if the databases are not published in replication. You must re-create any logins and other user objects in master, msdb, and model system databases.

If you have installed a default instance of SQL Server and wish to keep it that way your only option is to remove the current install and install using the 64-bit media. Otherwise you can install a 64-bit instance as a named instance on the same server.

Cindy Gross has some additional useful information here.