Installed Eclipse Android SDK Package (Latest Version: API Level 20), can't run programs that was woking before

I upgraded the Eclispse Android SDK that I downloaded last month and had been using until yesterday. I had a few programs working.

Earlier today, I tried to upgrade the ADT plugin, but failed and ended up with non-operable Eclispe, so I downloaded and installed the latest version available at Google's site for developers.

I imported one of the programs working before and I can't even run it now. I get three errors, all seem to be

I downloaded Eclipse indigo with ADT 22.06.2 a little over a month ago. I had a few projects that compiled and produced apps that apparently ran on BlueStacks.

Today, I downloaded Eclipse juno with ADT 23.02 .1259578.

I imported one of the projects that were working with the Eclipse indigo. Its stylesheets generates the following errors:

error: Error retrieving parent for item: No resource found that matches the given name 'Theme.AppCompat.Light'.

and

error: Error retrieving parent for item: No resource found that matches the given name 'Theme.AppCompat.Light.DarkActionBar'.

They occur in the following three stylesheets( they're the originals that came with one of “Hello World” type examples from Google's site for Android app developers):

<resources>

<!--
    Base application theme, dependent on API level. This theme is replaced
    by AppBaseTheme from res/values-vXX/styles.xml on newer devices.
-->
<style name="AppBaseTheme" parent="Theme.AppCompat.Light">
    <!--
        Theme customizations available in newer API levels can go in
        res/values-vXX/styles.xml, while customizations related to
        backward-compatibility can go here.
    -->
</style>

<!-- Application theme. -->
<style name="AppTheme" parent="AppBaseTheme">
    <!-- All customizations that are NOT specific to a particular API-level can go    here. -->
</style>

</resources>



<resources>

<!--
    Base application theme for API 11+. This theme completely replaces
    AppBaseTheme from res/values/styles.xml on API 11+ devices.
-->
<style name="AppBaseTheme" parent="Theme.AppCompat.Light">
    <!-- API 11 theme customizations can go here. -->
</style>

</resources>


<resources>

<!--
    Base application theme for API 14+. This theme completely replaces
    AppBaseTheme from BOTH res/values/styles.xml and
    res/values-v11/styles.xml on API 14+ devices.
-->
<style name="AppBaseTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <!-- API 14 theme customizations can go here. -->
</style>

</resources>

Apparently, importing the “android-support-v7-appcompat” [aclage which came with the new Eclipse package doesn't help.

When I import the project, I get two (not three) identical errors. They are:

[2014-07-27 18:27:00 - HOGLES200043] Unable to resolve target 'android-19' [2014-07-27 18:27:00 - HOGLES200043] Unable to resolve target 'android-19'

The manifest for this project is the following:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://ift.tt/nIICcg"
package="com.example.android.opengl0043"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="15" />

<uses-feature
    android:glEsVersion="0x00020000" android:required="true" />


<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.example.android.opengl0043.OpenGLES20Activity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

</manifest>

Is there something I'm missing here?

Thanks for your help.