(No implementation found for method canLaunch on channel plugins.flutter.io...)

enter image description hereI am building an application that uses firebase and share the content of the application The app was working fine and when I added the firebase packages I got errors:

MissingPluginException(No implementation found for method canLaunch on channel plugins.flutter.io/url_launcher)

MissingPluginException(No implementation found for method canLaunch on channel plugins.flutter.io/share)

MissingPluginException(No implementation found for method canLaunch on channel plugins.flutter.io/google_mobile_ads)

I have tried more than one method (flutter clean) many times (flutter pub get) many times (flutter run) (reinstall app) many times I searched for solutions but it didn't work

class Home extends StatefulWidget {
static String id = 'HomeScreen';
const Home({Key? key}) : super(key: key);

@override
_HomeScreenState createState() => _HomeScreenState();
 }

class _HomeScreenState extends State<Home> {

Future<InitializationStatus> _initGoogleMobileAds() {
return MobileAds.instance.initialize();
}


 late BannerAd _bannerAd;

 bool _isBannerAdReady = false;

  @override
  void initState() {
 _bannerAd = BannerAd(
  adUnitId: AdHelper.bannerAdUnitId,
  request: AdRequest(),
  size: AdSize.banner,
  listener: BannerAdListener(
    onAdLoaded: (_) {
    setState(() {
      _isBannerAdReady = true;
    });
    },
    onAdFailedToLoad: (ad, err) {
     print('Failed to load a banner ad: ${err.message}');
     _isBannerAdReady = false;
      ad.dispose();
    },
  ),
 );

 _bannerAd.load();
 enter image description here}


 @override
 void dispose() {
  _bannerAd.dispose();
  super.dispose();
 }}

I added ads in same class that has _launchUrl()

    _launchURL() async {
    const url = 'url';
    if (await canLaunch(url)) {
    await launch(url);
    } else {
  throw 'Could not launch $url';
   }
  }

and _share() method also

         onTap: () {
           Share.share(appUrl);
              },