In order to use two-way data binding for form inputs you need to import the FormsModule package in your Angular module.

import { FormsModule } from '@angular/forms';

@NgModule({
    imports: [
         FormsModule      
    ]

EDIT

Since there are lot of duplicate questions with the same problem, I am enhancing this answer.

There are two possible reasons

• Missing FormsModule, hence Add this to your Module,

  import { FormsModule } from '@angular/forms';
  
  @NgModule({
      imports: [
          FormsModule      
      ]
  

• Check the syntax/spelling of [(ngModel)] in the input tag

This is a right answer. you need to import 'FormsModule'

first in app.module.ts

**

import { BrowserModule } from '@angular/platform-browser';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { NgModule  } from '@angular/core';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    FormsModule,
    ReactiveFormsModule ,
    BrowserModule,
    AppRoutingModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

** second in app.component.spec.ts

import { TestBed, async } from '@angular/core/testing';
import { RouterTestingModule } from '@angular/router/testing';
import { AppComponent } from './app.component';
import { FormsModule } from '@angular/forms';
describe('AppComponent', () => {
  beforeEach(async(() => {
    TestBed.configureTestingModule({
      imports: [
        RouterTestingModule,
        FormsModule
      ],
      declarations: [
        AppComponent
      ],
    }).compileComponents();
  }));

Best regards and hope will be helpful.

Your ngModel is not working because it's not a part of your NgModule yet.

You have to tell the NgModule that you have authority to use ngModel throughout your app, You can do it by adding FormsModule into your app.module.ts -> imports-> [].

import { FormsModule } from '@angular/forms';

@NgModule({

   imports: [ FormsModule ],       // HERE

   declarations: [ AppComponent ],
   bootstrap: [ AppComponent ]
 })