Can't update files after changing from Windows 8 to Windows 10

Hopefully someone here can help!
Following a failure with Windows 8 my laptop was recently reinstalled with Windows 10 in order to keep the files already on it.
However, I can’t now get to the ‘start’ screen where I enter my password in order to start back up. The drive is open to view files already on it though.
Any help/guidance appreciated, or do I have to start from scratch?