accidentally deleted layers UE-27

I am new at unreal engine 4.27 I was learning use textures but one time layer colors stopped chancing colors example ı changed black to green or whatever but it still at black ı tried to solve but cant solve it ı get angier and deleted all other layers by an miss click button now it not showing layer even ı erased and putted the same code again break nodes, open close , switching tabs is not working please help