Add Global.asax file in your solution explorer and the the following code in Application_Start Section.4

 

ScriptManager.ScriptResourceMapping.AddDefinition(“jquery”, new ScriptResourceDefinition
{
Path = “~/scripts/jquery-1.7.2.min.js”,
DebugPath = “~/scripts/jquery-1.7.2.min.js”,
CdnPath = “http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.4.1.min.js”,
CdnDebugPath = “http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.4.1.js”
});