Yesterday it worked, today it doesn't. What gives?

Can't seem to find the pso2 launcher anymore? IT just magically disappeared.

update: i reinstalled the whole thing and it was fine. I was doing something after, so i restarted my pc. i tried to open pso2 after restarting and now it won't open.

Windows Update killed the game, and no fix seems to be working atm.

Use the tweaker app to check files and redownload the executables.