There may be a few issues here so I start from the beginning......
OK so first up you need to have completed the standard steps for setting up the M5Stack, located here
You should then have these directories installed:
If downloading using git, then in git go to directory location equivalent to C:\Users\your-user-name\Documents\Arduino - which from within git will be: ~/Documents/Arduino
git clone https://github.com/PartsandCircuits/M5Stack-SAM.git
Go to: C:\Users\your-user-name\Documents\Arduino\M5Stack-SAM\M5Stack-SAM and open the M5Stack-SAM.ino file in the Arduino "IDE".
[ Note that "Parts and Circuits" should not be part of any directory names on your machine ].
Connect M5Stack , select com port, then compile and upload to M5Stack.
( For anyone not using git just select Download and then move the files into the appropriate directory: C:\Users\your-user-name\Documents\Arduino ) Avoid using Arduinos zip install option.
You will need to be using M5Stack Library version 0.1.6 - some of the more recent libraries will probably not work, but 0.1.6 has been tested to work. I only recently became aware of this. I will make a note of this on the github page and will later try to update it.
To downgrade the M5Stack library version:
In Arduino, go to Sketch/Include Libraries/Manage Libraries then type M5Stack into the search field at the top.... it should then indicate which library version you have installed. If not 0.1.6 then click "Select Version" and select 0.1.6 and then select to install it.
Once you have the SAM menu loaded on your M5Stack you can then revert back to using a more recent version of the M5Stack library with the Arduino "IDE". I haven't noticed any problems resulting from moving between library versions.
OK hope that sorts this out for you.