Your artifacts are still there, don't worry. A few restarts fixes this. If that doesn't work, clear the cache and reinstall the game (make sure you have your account linked to Plarium before doing so).

Also I gotta ask what happened to your other account? If you had that game progress saved to a Plarium account using your email address it should still be there. 

i have this happen alot, the first thing I do is to fix the issues is the do a campain battle, at the end of the run go to edit team then look at your campain farmers stats and see if the gear loaded up for the run. most of the times it does, if not exit the game properly then restart. The cause of the issue is closing the game. i have the no gear issue about 50 percent of the time when i just close the game when a clan boos run fails its tune, that way i dont lose a key. like i said load a campain run it fixes it most of the time when the game loads the run, resets take to long and its taken me up to 12 reset to fix it that way