Unable to view Worddocument/pdf inside the Windowsstore app8.1

My windows8.1 store app needs to open word Document and pdf file in read only format from the customized path folder not in Assest. Code below

Encoding utf8 = new System.Text.UTF8Encoding(true, true);
            StorageFolder storagefolder = Windows.Storage.ApplicationData.Current.LocalFolder;
            StorageFile storagefile = await storagefolder.GetFileAsync(@"C:\sampledoc\sample_raw.txt");
            var options = new Windows.System.LauncherOptions() { DisplayApplicationPicker = true };
            await Launcher.LaunchFileAsync(storagefile, options);

While running the the above code getting below mentioned Errors

An exception of type 'System.IO.FileNotFoundException' occurred in mscorlib.dll but was not handled in user code Additional information: The filename, directory name, or volume label syntax is incorrect. (Exception from HRESULT: 0x8007007B)