casting object to generic List<> in c#

 Hi everybody,
 I am facing issue while casting cache object as generic list<> in c#. The code shown below.
List<Struct> _list = List<Struct>HttpContext.Current.Cache["ld_mn"];
The following compilation error arises on building.
Error    20    Using the generic type 'System.Collections.Generic.List<T>' requires '1' type arguments
Error    21    'Struct' is a 'type' but is used like a 'variable' 

Can anyone help me how to cast an object to List<> in c#.
Waiting for response.

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