I had a problem when trying to install/uninstall stuff on Ubuntu 20.04:

dpkg: error: error trying to open /var/lib/dpkg/info/format: Not a directory

E: Sub-process /usr/bin/dpkg returned an error code (2)

I saw this topic:

Lost/Deleted dpkg (package manager for Debian). How do I get it back?

But the website packages.ubuntu.com was down. Please tell me another website to download this dpkg.deb. I am using Ubuntu 20.04.
Please tell me how to find the exact version to download.
Thanks for all!