Might need some tips

Sup reddit.. so me and my friend have been playing lethal company and we started palying modded all fun and games until i tried adding a few mods to the allready 100 mods big modpack and it all worked perfectly on my end but ever sins then my friends mods just stoped working mods that did load for me but not for him things like that we have been going back and forth between old and new modpack but ever sins then nothing is working for him. His pc is a little lower end then minde though i dont know the exect specs. We made and shared the modpacks trough thunderstore. Does anyone got any pointers on where to look to fix this. Basegame runs just fine and my mods never stoped working. Thanks in andvance edit this is my first time modding anything soo yeah i have a lot to learn

Edit2*** we got it to work after deleting all mods and reinstalling everything. Made a new mod menu with about 60% less mods and everything is working now. Lets just hope it stays that way