Hi
You should re-construct missing object in the application layer, since it is missing & it can be done by any one of the option as below;
1) By re-transport - Check with your ABAP team for the transport, looks like they created this Z index (ZIR) for table IMRG & you can re-import the required transport request.
2) This should be performed by DDIC user, You can re-construct it from SE14 as below; -
SE14 -> objects IMRG --> Edit --> this will display the screen as per Siva's update.
From here, go to Menu opton "Table", then Select "Reconstrct" this should create the missing object at application layer or say runtime objects.
regards
Swami