assistant from Microsoft tried to help me
Are you clear on what he did "to help", did he offer any explanation as to why your computer would no longer start? OR suggestions as to how you might proceed?
I tried to rrstore and recovery but it always failed
Depending on what might have been fixed or further broken as a result of your attempts and "restore and recovery", you may be looking at a custom clean install of the Operating System.
However you decide to proceed, you a probably going to need the latest ISO from here
Use that ISO to create the installation media and then use that media to boot your system and then try the "Repair your computer" link on the second page of the installation process, to access the advanced troubleshooting tools and from there attempt first to boot the system into Safe Mode and see if that works.
IF not then you might try a System Restore
Sometimes the repair options seem to work better from the boot media, independent of the installed OS.
Failing all of that, backup your critical data and perform a custom clean install of Windows 10