Merhaba Zeynep,
büyük ihtimal ile AndroidManifest.xml dosyasında bir sıkıntı var.
<application
android:allowBackup="true"
android:largeHeap="true"
android:hardwareAccelerated="false"
android:icon="@mipmap/indoorex_ico"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity
android:name="your main activity"
android:configChanges="orientation|screenSize">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<action android:name="com.package.name.MyActivity"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
<activity android:name="your other activity"
android:configChanges="orientation|screenSize">
</activity>
<activity android:name="your other activity"
android:configChanges="orientation|screenSize">
</activity>
<activity android:name="your other activity"
android:configChanges="orientation|screenSize">
</activity>
<activity android:name="your other activity"
android:configChanges="orientation|screenSize">
</activity>
<activity android:name="your other activity"
android:configChanges="orientation|screenSize">
</activity>
</application>bu yapıda olması gerekiyor. Buna göre kontrolünü tekrar yapabilirsin. Kolay gelsin.