Seems for some unknown reason, your AV is sticking the game's .exe into quarantine.. probably due to overly restrictive heuristics enabled or is detecting false positives. What AV are you using? May be worth whitelisting the entire elsword folder (or if you're not on a paid AV, I can recommend an alternative if you're willing to switch)
Hey
Have you made any security changes recently? Can we have your windows version?
I'm not sure but you might have enabled some allowed security steps from your antivirus so it uninstalls the game by itself.
Actually, i haven't had any problem with my AV before, neither i did any security changes into it nor nothing. It keeps happening whenever i log into the game, and before the character's screen pops up, Elsword just stop running and no message is displayed, it just dissapear, then, Elsword.exe can't be found. Also, its Win 10 Pro Edition.