Unable to Log into Windows 10

This problem started with Windows 8.1.
I had to fit a new HDD operating 8.1, that was how it was when I
upgraded to W10.

After 6 or 7 hours of W8.1 checking and installing I got the PC going,
only to discover that when I went to any site, I was unable to enter
a password, when I start, the first two digits go in OK,but when I hit
the third letter it goes between the first two, at least that is where the
cursor lands, this happens on any site. I had my machine set to open
without a password, so that was why I could get in.

This fault prompted me to go ahead with the W10, which I installed.
Unfortunately it kept the setting that has screwed up my password
entry, but it didn't keep the "No sign in password", so now I can't even
get in to do anything, I have had to put the bad disc back in, in order
to try and get some help. Is there a key that I can hold down to force

Windows to repair itself at start up?

Thank you for reading this and I hope that somebody has a good idea
that will help me.

Mike.

You may want to try a new keyboard. 

Another option is to click the clock on the login screen and select On Screen Keyboard. Use that to enter your password then Enter.

Thanks for the suggestion John.

I will certainly try that when I put the new HDD back in.

Mike.