If you are unable to run Pub Commands after installing dart sdk, the probably you are missing the below steps. Please follow the below instructions to get it fixed.
Add the below 2 Environment variable
1) %APPDATA%\Pub\Cache\bin - Verify if the path has got stagehand.exe file.
2) C:\src\flutter\bin\cache\dart-sdk\bin - Verify if the path has got the dart.exe file.
Most of you must be already aware of what I'm going to do with this. Below is the screenshot of how your environmental variable is going to look.
The first path is where you find the stagehand file. And in the second path, you will find the dark.exe file. The second path may change in your case depending on where you extracted the flutter SDK.
In order to set the environment variable, you have to follow the below steps.
1) Open Control Panel.
2) Click on System.
3) On Left-hand side, click on Advanced system settings.
4) Go to Advanced Tab.
5) Click on Environment Variable button.
6) Select Path from the top list and Edit.
7) Click New again and key in the Paths. Repeat it twice.
That's it. Now you will be able to run the Pub Commands on your Windows machine.