sometimes AS would destroy that folder for no damn reason.
instead of rebuilding your project, rebuild just the manifests folder and xml file :

tool bar : file Right Click -> New -> Other > Android Manifest

in the new manifest .xml copy paste the contents from some other manifest file and fudge around with the package name field and the main activity field,
build.

Code:

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

          package="com.yotamarker.lgkotlin1">



    <application

            android:allowBackup="true"

            android:icon="@drawable/brain"

            android:label="@string/app_name"

            android:roundIcon="@mipmap/ic_launcher_round"

            android:supportsRtl="true"

            android:theme="@style/AppTheme">

        <activity android:name="com.yotamarker.lgkotlin1.MainActivity">

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />



                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

    </application>



</manifest>


package="com.yotamarker.lgkotlin1">  :cop3:  :guro:

<activity android:name="com.yotamarker.lgkotlin1.MainActivity">