re-download game?

I can't find the game(PoE1) installed anywhere on my pc, I may have uninstalled it after finding it far more complex a game than anticipated and NOT finding any real help in-game (community, clan/guild, helpful comments, etc) Anyone know what the executable to launch is or would I be better off just re-downloading the game .. hopefully without additional cost to me. I can't recall last time I logged in but was about the release date of D4.

Also, if I do have to re-download/install will I have lost the extra storage tabs I had purchased?! ??