Automatic Repair couldn't fix your PC?

When I tried to start my laptop (Toshiba) today I got an error message that the automatic repair could not repair my PC. So my question is: How can I repair my laptop without erasing data?

You could start from a Windows CD or a bootable USB with windows and then press repair with a little luck it will work

Either load a restore point using the options, or else restart the system. As long as the hard disk is not formatted, all user data should still be available after reinstalling Win 10 - just not in the newly installed instance, but in the old one. Otherwise there are backups.