Android Studio cannot resolve symbols

Question

At first i had to rename the .png file names because they were not acceptable. Now that i have renamed them and change the name on the code i still get an error that my drawable 'd6' etc cannot be found. I have tried restarting my application and look for the issue but, I cannot seem to find the problem.

In case this is relevant:

 xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:orientation="vertical"
    android:background="@drawable/background"
    android:padding="10dp"
    android:id="@+id/diceContainer">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tvHelp"
        android:layout_marginLeft="10dp"
        android:layout_marginTop="18dp"
        android:layout_marginRight="10dp"
        android:background="@drawable/back"
        android:gravity="center"
        android:padding="5dp"
        android:text="Touch on the screen to start rolling."
        android:textColor="#ffffff"
        android:textSize="18sp" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"
        android:orientation="vertical" >

        <ImageView
            android:layout_width="150dp"
            android:layout_height="150dp"
            android:id="@+id/die1"
            android:layout_marginBottom="15dp"
            android:src="@drawable/d6" />
        <ImageView
            android:layout_width="150dp"
            android:layout_height="150dp"
            android:id="@+id/die2"
            android:layout_marginBottom="15dp"
            android:src="@drawable/d6" />


    </LinearLayout>




</LinearLayout>

public class MainActivity extends AppCompatActivity {

    int delayTime =20;
    int rollAnimations = 40;
    int[] diceImages = new int[] {R.drawable.d1,R.drawable.d2,R.drawable.d3,R.drawable.d4,R.drawable.d5,R.drawable.d6};
    Random random = new Random();
    TextView tvHelp;
    ImageView die1;
    ImageView die2;
    LinearLayout diceContainer;
    MediaPlayer mp;

These are also some screenshots below :

I tried renaming the files and restarting android studio.