It's probably the Keybindings. This also happened to me when I changed the key to DFJK without realizing F was already bound to Fullscreen. It really seemed to hate having a key binded to two things and did basically exactly what's happening to you as a result.
If you wait like 10 mins it SHOULD get past the initial not responding thing and actually start and maybe you can fix the key bindings from there. If not then go into Appdata/Roaming/FunkinCrew and move Funkin1.sol out of the folder(basically your save data and config stuff) and the game should start. You might be able to move it back in after that and change but for me I just deleted it and dealt with erasing my high scores.
Glad I could help lol.
I had a very very similar experience to you and was equally baffled that I somehow broke the game changing keybinding.
The devs really need to put a failsafe to prevent that issue. Or at least make the config file something separate from save data and editable with notepad like a lot of games do. So you can fix the issue without deleting all your progress.