The Problem is that I have a web reference genereted from WSDL file. Now I have new WSDL but the old location where the WSDL was erlier is not accesible. Where I can change the path to the new WSDL to do update web reference? When I delete my old web reference and add new one with the same name, I don't see the web reference namespace anymore in code classes...any ideas??
It depends on what type your reference is.
If it's a Service reference, then you can change it by right click on that reference and choose "Configure Service Reference". In service reference settings window you will see "Address" field. There you can change your service reference address.
If it's a Web reference, then select that web reference and press F4 key to open Properties window. There you can change your web reference url address.