when I try and run pywallet, it flashes on the screen and disappears,
Can you open Windows Search (press Windows key + S or click on the magnifying glass at the bottom left), type "cmd", and then click on the entry with the console icon that says "Command Prompt" or "cmd"?
This will open a command prompt window where you can use the
cd C:/Users/you/Downloads/whereverPywalletIs command to go to the folder of pywallet, and then try to run it again. It should not flash and disappear this time.