password problem at startup

[francis - thuis]

Hi All,
I`m new in (k)ubuntu world, I decided that my new laptop would be a 
linux one and that's how I got kubuntu. Please note that I am an advised 
user of computer-programs but I am certainly not an expert in setting up 
these things. Think about this before answering me, thanks.

My prolemm is that when  I got a passwordt for it. I changed the 
password, saved it and wrote it down on paper for memory..
Now when I am starting the computer again the kubuntu login page comes 
up and I have to onsert my login name and password.
When, I do this it says that it fails. I tried more than once and also 
again wiith te first password that came with the computer.
Nothing works.

So I have a few questions:
1. how can I find the correct login/password?
2. how can I eventually start from scratch again? (as there is not yet 
anything on the computer, I won't loose anything)
3. can I, after that I succeded again to work on the computer, adapt the 
system so that it doesn't ask passwords again?

thanks for a quick answer.
Francis