I've had this happen earlier this year, I moved my mods and custom content to a folder on the desktop for safe keeping and went through it little by little, trying to find out which files were causing the issue. Which was the game not loading.
I went with my mods first and after that I went through my custom content. Here's the steps I took:
1. I copied the files back in small batches of 3 or 4 files at a time.
2. Deleted the game cache files before putting in each batch of files.
Delete Game Cache Files (What & Howto)
https://www.carls-sims-4-guide.com/forum/index.php?topic=20732.msg401809#msg4018093. Launched the game to see if it would load. When it loaded, I went back through and did steps 1 and 2 again until I went through all my mods and custom content.
For different ways to go through your mods/cc, see the article linked below:
Game Help:TS3 Finding Problem Custom Content
http://simswiki.info/wiki.php?title=Game_Help:TS3_Finding_Problem_Custom_Content