Unfortunately many other people are having this issue as well.
From this point on until Blizzard decides to re-release a classic tft client, you’ll be stuck with the new Reforged client. This basically means you are forced to play reforged but with the new graphics turned off. This also includes playing with all of the original client features gone.
If you want to revert to the old client and just play using pvpng services (like gameranger or Wc3Connect) or using LAN you can figure out how to do that here: For those who want to play Classic Warcraft 3
Unfortunately this means no BNET play, but its better than nothing.