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Psychopy does not open

Hi everybody. I removed my python 3.8 in my system and reinstall another version (3.6) and now psychopy doesn’t open and gives an error telling: psychopy the application was unable to start correctly.
And when I want to open a pre-created psychopy file it gives back: “this file does not have an app associated with it for performing this action. Please install an app or, if one is already installed, create an association in the Default Apps Settings page.”
Would you please help me solve this problem?