ZDoom

Since I am using a Mac, I am usually just running GZDoom by clicking on the application and starting the game by pressing OK. Would you like to see a video that demonstrates the specific problem that I'm dealing with?

From time to time https://doomwiki.org/ comes in handy.
See https://doomwiki.org/wiki/DOOM2.WAD to compare to your Doom2.wad
Hopefully your file is still okay.

No need to reinstall GZDoom. We need more information - as it's extremely unlikely (in fact, impossible) that GZDoom overwritten your IWAD files. How are you launching GZDoom? Are you using a .bat / bash (linux) file, a shortcut or a GUI launcher like ZDE, DoomRunner or ZDL?

A few days ago I was trying out this Wolfenstein 3d mod on GZDoom. At some point I was trying to run an addon that it had and I was having issues. The mod's file extension was originally ".ipk3" but I changed to pk3 when I first tried it as my GZDoom was having trouble running it the other way. When I downloaded the add-on for the mod I thought that it would work better if I used the parameter -iwad 'MODNAME' on the mod file and run it on the Doom 1 IWAD. This did not work at all and the game ran like regular Doom 1 but had a few conversions from the mod carried over (in my best way of describing it). I then tried with the Doom 2 IWAD with the same result. Both IWADs are now stuck like this permanently and this also causes any other mod that I import into GZDoom that uses the Doom 1 and 2 IWADs to not work. The Heretic IWAD is perfectly fine as I did not use the -iwad parameter on that IWAD. I'm not sure what to do and I'm considering reinstalling GZDoom entirely. Is there anyway to fix this without a reinstall?


the mod:
https://forum.zdoom.org/viewtopic.php?t=4608