1. Build a clean Forge profile first
A normal Verity Mod TLauncher install should start the same way as a normal Java install: create or select a clean Minecraft Java profile that matches the source file. For the current main Java route, that means Forge 1.20.1. Launch that profile once with no Verity file at all. If the game cannot reach the menu, the problem is the profile, Java runtime, loader install, or TLauncher configuration. Adding the mod before this first launch makes the failure harder to diagnose because you will not know whether the base game or the mod caused it.
After the clean profile opens, close Minecraft and locate the mods folder for that exact profile. Do not use a global folder copied from another launcher without checking the path. TLauncher guides often show one folder location, while your operating system, profile name, or portable install may use another. If the JAR is in the wrong folder, Minecraft can start normally but Verity will never appear in the loaded mod list.