Of course if your sole access is via a putty connection ie you are running your Raspberry headless you won't be able to run raspi-config until you have figured the SSH connection.
In the Putty configuration window in the Left panel there is a section labelled Connection with a subsection SSH
This has two options 2 which is my default and 1 which is also labelled as (INSECURE).
I make no guarantee that this is the answer but it may be.
Remember if all else fails you can image either a new SD or re-image your existing SD if it has no saved data.
This will take your SSH login back to the default and at that stage you can reset your password to something other than the default.
The whole point of having the Operating System on an SD card was that swapping it out or having multiple copies was no big deal.
It would probably be a good idea to get yourself familiar with the setup before you try changing passwords. It is not like you are running anything vital if you are you should probably not be doing this on a Raspberry at least until you are thoroughly familiar.
I am afraid I don't qualify as a 50 year old as I passed that milestone over 10 years go.