Exception At the start up of the android application in Xamarin - xamarin

Question

I am new to Android Development in Xamarin. I have created a sample application and it was running fine. But suddenly i got the below error which i am not able to figure out what to do. I did not get any solution from internet. I have reinstalled everything but no luck. Please help!
Java JDK 1.7.0
Android SDK 22.0.0
GTK# 2.12.26
Xamarin Studio 5.9.4
Xamarin 3.11.666
Error:
Java.Lang.RuntimeException: java.lang.reflect.InvocationTargetException
at --- End of managed exception stack trace ---
at java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
at at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at at dalvik.system.NativeStart.main(Native Method)
at Caused by: java.lang.reflect.InvocationTargetException
at at java.lang.reflect.Method.invokeNative(Native Method)
at at java.lang.reflect.Method.invoke(Method.java:515)
at at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at ... 2 more
at Caused by: md52ce486a14f4bcd95899665e9d932190b.JavaProxyThrowable: System.ArgumentNullException: Argument cannot be null.
at Parameter name: value
at at Newtonsoft.Json.Utilities.ValidationUtils.ArgumentNotNull (object,string) <IL 0x00009, 0x0006c>
at at Newtonsoft.Json.JsonConvert.DeserializeObject (string,System.Type,Newtonsoft.Json.JsonSerializerSettings) <IL 0x00006, 0x00067>
at at Newtonsoft.Json.JsonConvert.DeserializeObject<Tasky.Core.UserData> (string,Newtonsoft.Json.JsonSerializerSettings) <0x00063>
at at Newtonsoft.Json.JsonConvert.DeserializeObject<Tasky.Core.UserData> (string) <0x0006b>
at TaskyAndroid.Screens.HomeScreen.OnCreate (Android.OS.Bundle) [0x00017] in f:\Solutions\Xamarin\Tasky\Android_Starter\TaskyAndroid\Screens\HomeScreen.cs:60
at Android.App.Activity.n_OnCreate_Landroid_os_Bundle_ (intptr,intptr,intptr) [0x00011] in /Users/builder/data/lanes/1879/5f55a9ef/source/monodroid/src/Mono.Android/platforms/android-10/src/generated/Android.App.Activity.cs:1777
at at (wrapper dynamic-method) object.6147fbee-1dc5-4093-b962-ef4f61496551 (intptr,intptr,intptr) <IL 0x00017, 0x00043>
at at md5b8e170d2a8045dd039dc8ae8a9f57934.HomeScreen.n_onCreate(Native Method)
at at md5b8e170d2a8045dd039dc8ae8a9f57934.HomeScreen.onCreate(HomeScreen.java:29)
at at android.app.Activity.performCreate(Activity.java:5231)
at at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
at at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
at at android.app.ActivityThread.access$800(ActivityThread.java:135)
at at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at at android.os.Handler.dispatchMessage(Handler.java:102)
at at android.os.Looper.loop(Looper.java:136)
at at android.app.ActivityThread.main(ActivityThread.java:5001)
at ... 5 more