几天前，我使用了以下代码，并且工作正常，但是现在它无法识别以前识别的任何音频文件。我想知道怎么了？

import speech_recognition as sr

r = sr.Recognizer()

audio_file_name = 'audio.wav'
audiofile = sr.AudioFile(audio_file_name)
with audiofile as source:
    audio = r.record(source)
    try:
        text = r.recognize_google(audio)
        print("i: {}   You said : {}".format(i+1,text))
    except:
        print("Sorry could not recognize what you said")