React Native "Cannot find module 'react-native'" Problem

Question

I just started to React Native and I'm coding To Do List. I installed react-native module and global cli. But when i write "npm start", I'm taking error "Cannot find module 'react-native'"

this is my App.js File. Thank you...

import React from 'react';
import { SafeAreaView, View, Text} from 'react-native';
function App() {
return (
<SafeAreaView 
style={{
  flex:1, 
  alignItems: 'center', 
  justifyContent: 'center'}}>
      
      <View 
        style={{
        flex:1, 
        alignItems: 'center', 
        justifyContent: 'center'}}>
      </View>
      
      <View style={{flex:3}}>
        <Text>Kayıt Listesi</Text>
      </View>
      
</SafeAreaView>    
  );
  }
  export default App;