He most likely fell for the 2d game scam. Basically for those who don't know, a hacked account will message accounts on its friends list. The hacked account will ask for help testing a game and will send a exe, which is in actual fact malware. When the user launch this "game", it'll steal your discord account token along with any passwords saved in chome.
Here's some tips on order to make sure you don't fall victim to this shit:
1: Think, is your friend actually smart enough to develop a game? If no, he's hacked. If yes, remain skeptical and ask questions. If he's not talking like he usually would, he's probably hacked.
2: Do not download and launch any software you don't trust. You don't know what's hiding inside it.
3: If you do launch this malware, reset your passwords for everything and contact your friends before the hacker does
TL:DR: Don't launch random shit you get sent. Use your brain, most of you have one. And think, is your friend smart enough to develop a game?