why Microsoft.office.interop.word with .net framework 4.5.2 works fine locally but not running on server?

I am working on an application where I make my system to generate a report as word document. For this I've used microsoft.office.interop.word through nuget package manager. It is running fine locally but when I published my changes on server it started showing me below error:

     "Retrieving the COM class factory for component with CLSID {00024500-0000-0000-C000-000000000046} failed due to the following error: 80070005 Access is denied." (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED)).

My system admin made some some admin rights related changes on server and instead of this error I started getting below error

    Object reference not set to an instance of an object

after getting this error I checked with server db and was able to generate file locally but not on test server.

Can anybody suggest me something?