theme breaks

hello, my theme breaks when I turn cache on
I try to debug this issue by disabling every other feature, and by only turning cache
I still get the issue, plugin was working fine dont know what happend.
btw all other caching plugins dont work and dont cache my website even tho define Wp cache is set to true in wp config file, only wp fastest cache works and does save cache files in my wp content/cache folder.
so I really need help with this problem.
thanks