I installed Android SDK Manager two months back. I got the Android 2.3.3 SDK installed, but I do not quite remember the steps I followed, because I am new to Android development. Now, when I open Android SDK manager, I see only the "SDK Platform Android 2.3.3". I cannot see any other API versions which I am interested in (eg. higer versions). However, I do not see any options for selecting any other API versions. I have already tried the following:
1) Tried to locate "Available Packages" option, but I cannot locate this option in Android SDK Manager.
2) Tried Tools -> Options -> "force https://...sources". After doing this, it connected to this URL but the View remains the same,i.e I cannot see a list of available packages that I can install. I have not given any proxy address in the boxes.
3) I have run the Android SDK manager with administrator privilege.
4) I am not running Android SDK manager from eclipse, i.e. I am running it directly. (at the time of writing I am downloading eclipse again because I had uninstalled it. So, I haven't tried opening Android SDK manager from eclipse).
I am attaching the screen shot of the Android SDK manager. (with the version number of SDK manager in the About dialog box)
Go to Help -> Install new software
Click on Add button
Add the link http://dl-ssl.google.com/android/eclipse
Expand Developer tools. Inside that select Android DDMS and Android Developer Tools
Uncheck Show only latest versions
Click finish...
Restart eclipse .
Go to Help -> Check for updates. Complete all the updates
Then go to Window -> Android SDK Manager
You'll find all available versions..
If some API levels are not listed in Android SDK Manager (API 14 for example) try to check Obsolete check box on the bottom of the Android SDK manager window.
来源：https://stackoverflow.com/questions/14169027/additional-android-apis-not-shown-in-android-sdk-manager