I need to retrieve my previous password. I saved a new one in error not realizing it's not valid

HI Andrew,
It did seem odd that password history wasn't available (still isn't) on my Mac but I was relieved when it occurred to me to try the iphone and found it there. I'm such a low-level user of tech generally, I can't say I'd noticed anything else unexpected but now I have contact with you, if you don't mind, I'll come and say Hi if I do have any queries.
When I clicked on the link you shared, I got another Server not found error and this message: Hmm. We’re having trouble finding that site.

We can’t connect to the server at my.undefined.

If you entered the right address, you can:

Try again later
Check your network connection
Check that Firefox has permission to access the web (you might be connected but behind a firewall)

At the moment 1Password appears to be working fine though.
Kate