Accidentally deleted graph of SketchupMaster material in Editor. Please HELP!!

Hi, so I accidentally deleted the graph of SketchupMaster material and plugged in some white colour with reflections. Now all my materials are white with reflections and I am unable to revert back to old textures.

I even reopened Unreal and reimported datasmith files (exported from sketchup) into it but it all just comes out pure WHITE. How do I resolve this? Thanks in advance