This forum is about Avast Passwords application, according to symptoms it seems that you have problem with Avast Anti-Theft pin
Try follow this guide
https://www.avast.com/faq.php?article=AVKB127#artTitle
Or ask for additional help in here:
https://forum.avast.com/index.php?board=37.0
Or/And
https://forum.avast.com/index.php?board=38.0