The main problem is I can't remote my server via ssh.
Remove the content of /root/.ssh/known_hosts
If you wanna avoid that next time, create a startup script.
A power down is never a software problem.
Create a new file under /etc/init.d/, call it anything, myscript.sh as example.
Add it to the rc.local like this echo "/etc/init.d/myscript.sh" >> /etc/rc.local
While is not the proper solutions, it works.
My recommend is to don't wait for solutions when you have a problem.
Put the solution before it, bui a SAI for your office.