Some parts like the SC-B-ICPS, fuel tanks and other stuff dont exist when i search for them. I dont know if its clashing with another mod because i am using a lot of them.

I'm guessing this is in reference to updating from a prior KSP version (KSP 1.3.x?)?

The parts you are referring to have either been removed from the mod entirely (ICPS), or had their part-names changed.

There is no direct upgrade path between 1.3.x and current versions; too many parts have changed.

Also, duplicate of #732