Where do I sign in? What if I can't remember my password, how do I reset it?
You should be able to log in here, where "subdomain" is replaced with your own account's subdomain: https://subdomain.zendesk.com/access/normal
If you can't remember your password to log in, then you can reset it here: https://subdomain.zendesk.com/access/help
What if I'm being prompted to enter my current password?
If the browser is asking you for your current password to reset it and not letting you out of this particular page, there are a few things you can try to help work around this.
Firstly can you please try go to https://subdomain.zendesk.com/access/logout/ in your browser to see if it will force log you out of your Zendesk account. Then proceed to https://subdomain.zendesk.com/access/help.
If this does not work the next step is to clear your browser cookies and cache. Please give this a try as well.