platform-tools\\aapt.exe directory missing in android SDK

*What version of the SDK are you running? (1.5_r2 or something?)*

I would suggest updating your SDK and be done with it ;) You can do so trough the "Android SDK and AVD Manager".

Eclipse:
menu->window->"Android SDK and AVD Manager"

You might also want to change this setting:
menu->window->preferences->install/update->(expand)->automatic updates

Totally agree with izzy, but other times (usually on 64 bit OS machines or with multiple android platforms) when you install the latest SDK version the folder platform-tools had missing the "appt.exe".

To solve this you need to search on *android-sdk\build-tools* folder and subfolders like \build-tools\17.0.0 in my case, and you will find aapt.exe, other necesary files and lib folder, just copy it everything to android-sdk\platform-tools and it will be done.

sometimes you may get the error that it can not install because it can not create the temp folder to install the tools. You simply just need to run the SDK manager as administrator and this will allow it to all work out.

Run the Android SDK Manager and be sure that you have checked and installed Tools>Android SDK Platform-tools.

I believe this package is responsible for the folder in question here.

I just found aapt.exe file in my latest Android-SDK folder (Android_SDK\build-tools\28.0.3)

You can check your latest sdk build-tools folder
or
You can search on total Android SDK folder by file name

if we will face appt.exe issue (could not found) just Follow the below steps: 1. Just Read It(https://developer.android.com/studio/command-line/aapt2)

  1. Navigate to (ctrl+find and search) com.android.tools.build > then go to aapt2 from this url (https://dl.google.com/dl/android/maven2/index.html)

    1. Insert the version name you copied into the following URL and specify your target operating system: https://dl.google.com/dl/android/maven2/com/android/tools/build/aapt2/aapt2-version/aapt2-aapt2-version-[windows | linux | osx].jar For example, to download version 3.2.0-alpha18-4804415 for Windows, you would use: https://dl.google.com/dl/android/maven2/com/android/tools/build/aapt2/3.2.0-alpha18-4804415/aapt2-3.2.0-alpha18-4804415-windows.jar
  2. Extract the jar file, Change the name aapt2.exe to apt.exe

  3. Copy and paste into your android-sdk -> platform-tools

  4. Run the program, Issue will be get resolved

Note: Means you have to download and set the aapt.exe path in System Environment Variable