but it was already good to read and to understand
No, no it wasn't a good question. Why was it not a good question?
Assemblies (Namespaces) used for retrieving XML file?
- retrieving it from where? to do what?
Which Assemblies (Namespaces) should I use to access the XML file?
- access it to do what? (it's important to list a goal to help other understand what you're doing and thus help determine if you're approaching something incorrectly)
its showing error in Root.
- What is the exact error message?
- Is the error seen while compiling, linking, or running the code?
i used System.Xml still its showing error
- How did you attempt to use it?
- Is it the same error message as before or a different one?
The point here is detail is missing. You made some improvements on the post sure, but the raw details of what was desired should have been put in by the OP and without that it's a poor question at best.
Does it mean that such a questions with many dovnvotes are close automatically?
No, it means users voted to close the question. Specifically users:
Soner Gönül. If more/enough details is provided then it could be reopened, but as it stands I don't see a reason to do so.