Could you upload the psyexp file here so we can see it? My guess is, indeed, that you’ve saved the python script with the psyexp extension, so you’re trying to load a python script in Builder (won’t work).
If that is the case, and if you have a psydat file from a time when your experiment wa successfully running then we might be able to extract your original builder experiment from that (PsychoPy attempts to save your study within the psydat data files). So you could post one of those as well if you have one.