my game is continuously loading which is making me unable to go into build mode

@celestlaHiya 🙂
Did you do these things first?
EA APP \ repair
Delete thumbcache
start new game and test SIM

Did you do try a clean ( mod free  with clean thumbcache ) game?

*Mods do not need to be deleted, just removed from interfering to be clean game *
Check for broken mods via the list here under pinned above.
https://answers.ea.com/t5/Game-and-Mod-CC-Issues/Broken-Obsolete-and-Updated-Sims-4-Mods-1-104-Jan-16-2024-Game/m-p/13400494#M57563
Check on DISCORD on Deaderpool's channel for a comparison broken mods list if you use a wider genre of mods.
Update all core mods as needed.

If you have removed mods already... delete the thumbcache and using EA APP do a repair.
If still not working correctly... you need to remove all mods / trays / saves to desktop or rename them (see below ) then delete the thumbcache again, repair again and start a new game with a new test sim.
Then you can add mods back 50 / 50 until you find a culprit.
Then your trays and saves.
OR
~Close the game
Rename Documents\Electronic Arts\The Sims 4 to Documents\Electronic Arts\The Sims 4_Old
Repair the game
Start the game. All your content will be gone now as the game created a new folder. All your saves/.. is still in the old folder so not to worry
Start a new save game
Check if you still have the error
Report back with your results for further steps on how to get your stuff back.~ quote from crinrict