diff --git a/src/main/java/device/cdPlayer/CDPlayer.java b/src/main/java/device/cdPlayer/CDPlayer.java
index 304d03d..ca99dfb 100644
--- a/src/main/java/device/cdPlayer/CDPlayer.java
+++ b/src/main/java/device/cdPlayer/CDPlayer.java
@@ -25,6 +25,9 @@ public class CDPlayer implements Device {
 
     private List<String>favoriteSongs=new ArrayList<>();
 
+    private boolean muted=false;
+    private int oldVolume=0;
+
     @Override
     public void louder() {
         if(volume < 100) {
@@ -109,12 +112,18 @@ public class CDPlayer implements Device {
 
     @Override
     public String mute() {
-        return null;
+        muted=true;
+        oldVolume=volume;
+        volume=0;
+        return ("Volume muted.");
     }
 
     @Override
     public String unmute() {
-        return null;
+        muted=false;
+        volume=oldVolume;
+        oldVolume=0;
+        return ("Volume unmute.");
     }
 
     @Override
@@ -229,4 +238,13 @@ public class CDPlayer implements Device {
     public List<String> getFavoriteSongs() {
         return favoriteSongs;
     }
+
+    public boolean isMuted() {
+        return muted;
+    }
+
+    public int getOldVolume() {
+        return oldVolume;
+    }
+
 }
diff --git a/src/test/java/device/cdPlayer/CDPlayerTest.java b/src/test/java/device/cdPlayer/CDPlayerTest.java
index c3cda36..06cdff8 100644
--- a/src/test/java/device/cdPlayer/CDPlayerTest.java
+++ b/src/test/java/device/cdPlayer/CDPlayerTest.java
@@ -493,7 +493,7 @@ class CDPlayerTest {
 
     @ParameterizedTest
     @MethodSource("addToFavoriteSongsData")
-    void addToFavoriteSongs(String testName,String cases, CDPlayer _cdPlayer,Exception exception) {
+    void addToFavoriteSongsTest(String testName,String cases, CDPlayer _cdPlayer,Exception exception) {
         if(cases.equals("Case1")) {
             String myFavoriteSong = _cdPlayer.getCD().getPlayList()[0];
             _cdPlayer.addToFavoriteSongs(myFavoriteSong);
@@ -531,4 +531,78 @@ class CDPlayerTest {
         );
     }
 
+    @ParameterizedTest
+    @MethodSource("muteTestData")
+    void muteTest(String testName,String cases, CDPlayer _cdPlayer,String expectedResult) {
+        if(cases.equals("Case1")) {
+            assertThat(_cdPlayer.mute()).describedAs(testName).isEqualTo(expectedResult);
+        }
+        if(cases.equals("Case2")) {
+            _cdPlayer.mute();
+            assertThat(_cdPlayer.isMuted()).describedAs(testName).isEqualTo(true);
+        }
+        if(cases.equals("Case3")) {
+            _cdPlayer.louder();
+            _cdPlayer.louder();
+            _cdPlayer.mute();
+            assertThat(_cdPlayer.getVolume()).describedAs(testName).isEqualTo(0);
+        }
+        if(cases.equals("Case4")) {
+            for (int i = 0; i < 5; i++) {
+                _cdPlayer.louder();
+            }
+            _cdPlayer.mute();
+            assertThat(_cdPlayer.getOldVolume()).describedAs(testName).isEqualTo(5);
+        }
+    }
+    static Stream<Arguments> muteTestData () {
+        CDPlayer cdPlayer1 = new CDPlayer();
+        return Stream.of(
+                Arguments.of("[mute() by checkingTheReturnValue ] => ShouldReturnAString", "Case1", cdPlayer1, "Volume muted."),
+                Arguments.of("[mute() by checkingTheEffectAfterRun ] => VariableMutedShouldBeTrue", "Case2", cdPlayer1, "Volume muted."),
+                Arguments.of("[mute() after 2x louder() by checkingTheVolume] => VolumeShouldBeSetTo0", "Case3", cdPlayer1, "Volume muted."),
+                Arguments.of("[mute() after 5x louder() by checkingTheSavedOldVolume] => getOldVolumeShouldReturns_5", "Case4", cdPlayer1, "Volume muted.")
+        );
+    }
+
+    @ParameterizedTest
+    @MethodSource("unmuteTestData")
+    void unmuteTest(String testName,String cases, CDPlayer _cdPlayer,String expectedResult) {
+        if(cases.equals("Case1")) {
+            assertThat(_cdPlayer.unmute()).describedAs(testName).isEqualTo(expectedResult);
+        }
+        if(cases.equals("Case2")) {
+            _cdPlayer.unmute();
+            assertThat(_cdPlayer.isMuted()).describedAs(testName).isEqualTo(false);
+        }
+        if(cases.equals("Case3")) {
+            for (int i = 0; i < 5; i++) {
+                _cdPlayer.louder();
+            }
+            _cdPlayer.mute();
+            _cdPlayer.unmute();
+            assertThat(_cdPlayer.isMuted()).describedAs(testName).isEqualTo(false);
+            assertThat(_cdPlayer.getVolume()).describedAs(testName).isEqualTo(5);
+        }
+        if(cases.equals("Case4")) {
+            for (int i = 0; i < 6; i++) {
+                _cdPlayer.louder();
+            }
+            _cdPlayer.mute();
+            _cdPlayer.unmute();
+            assertThat(_cdPlayer.isMuted()).describedAs(testName).isEqualTo(false);
+            assertThat(_cdPlayer.getOldVolume()).describedAs(testName).isEqualTo(0);
+        }
+    }
+    static Stream<Arguments> unmuteTestData () {
+        CDPlayer cdPlayer1 = new CDPlayer();
+        return Stream.of(
+                Arguments.of("[unmute() by checkingTheReturnValue ] => ShouldReturnAString", "Case1", cdPlayer1, "Volume unmute."),
+                Arguments.of("[unmute() by checkingTheEffectAfterRun ] => VariableMutedShouldBeFalse", "Case2", cdPlayer1, "Volume unmute."),
+                Arguments.of("[unmute() by 5x louder()-> mute()] => getVolumeShouldReturn_5", "Case3", cdPlayer1, "Volume unmute."),
+                Arguments.of("[unmute() by 6x louder()-> mute()] => getOldVolumeShouldReturn_0", "Case4", cdPlayer1, "Volume unmute.")
+        );
+    }
+
+
     }
\ No newline at end of file