Thanks for the response. Finally the issue is resolved.

Successfully installed CU13 for one instance on the server.

I followed the workaround to copy sql server 2008 r2 native client dll(sqlncli10.dll) from other servers and CU13 was successful. Finally CU13 was successful for one instance and i will install CU13 on remaining instances tomorrow after server reboot as setup needed server reboot.

Below were the list of work arounds followed to resolve the issue.

The workaround on step7 finally resolved the issue:-)

"1. Repaired the shared features still CU failed with same error"

"2.Repaired the sql server instance for one instance and it

failed with same error"

"3.Tried Uninstalling sql server native client and then reinstalled it

http://social.technet.microsoft.com/Forums/sqlserver/en-US/8f08ffe1-da21-4e90-b1ca-07a430332975/sql-server-2008-r2-sp2-cu11-failing-with-error-patch-installer-failed-to-update-the-shared-features?forum=sqldatabaseengine. After reboot CU again failed with same error"

"4. Looked for Missing MSI/MSP files. There are no missing

MSI/MSP files"

"5.Changed the sql server agent to local system and back to

service account and tried applying CU. CU failed with same error"

"6.uninstalled existing CU4 and tried directly installed Cu11.

Still fails with same error"

"7.Copied the sqlncli.dll from other server

to system32. Reinstalled CU and it was successful"