While upgrading my Ubuntu from 18.04 to 20.04 it stopped responding and I forced it to restart and it is showing error

Question

I lost my complete iOS.

Oh no! Something has gone wrong
A problem has occurred and the system can't recover. Please contact a  
system administrator.

Answer 1

A release-upgrade is the worst possible time for a crash or interruption. Your system may be left unbootable (like yours).

The easy way to fix it is to boot a 20.04 installer and reinstall Ubuntu. Don't erase your disk, just install 20.04 in the existing filesystem.

• Warning: If you mistakenly choose to erase your disk, you will delete all your personal files, mail, browser profiles, and other data, likely irretrevably.

A more complex and slower way to fix it is to boot a LiveUSB into the "Try Ubuntu" environment, mount the disk, chroot into the broken system, and then run an apt dist-upgrade.