admin panel access

Hi,

I am new to this so be gentle!
I have installed WordPress, filled in the relevant bits on the config page. Installed it as instructed along with alkl the files & all appears ok. Tried to log into the admin but it tells me my password isn’t valid. SEnt for a new password but the page comes up with; Sorry, that key does not appear to be valid.

It didn’t ask me to set a passord up at the setup as it stated WordPress was already installed.
How do I either get a password or find the one I have?

Regards
Richard