Heeeyhey,
Its impossible to erase the levels, progress, ranks, dlcs and unlocks. They are not stored locally but on the Steam Servers.
I guess some connection issue happened. Its best to do a full reinstall and manually remove the game folder to clear all caches.
Then, check the firewalls and Anti Virus exceptions, check the Steam settings if they are set to default and ask your friend to do a reinstall of the game.
Also, please ask your friend to make sure be is plahing on Hell Let Loose, and not Hell Let Loose Public Testing.
Thaaanks!