My Web-to-Lead function stopped working after I changed my admin password, why?

The Admin password affects web-to-crm functionality.  For security reasons you would need to regenerate the code and use the new password when doing so, but your web developer will need to re-paste the new code into your web form.

This is a security measure to prevent unauthorised hacks through the web to lead page when admins change passwords.

You can do this in Setup, Lead Settings, Web to Lead.