@d-healey @ulrik Hey guys i sorted it. I found an even easier way.
I closed the project and opened up HISE again and then clicked View>Reset Workspaces and closed HISE.
I then opened HISE up again and Property Editor now appears again. Thanks so much for your help ,Much appreciated
David you are an absolute legend. Its working now! Thank you so much 
So just so i am clear for the future. where i went wrong was by using .length again in place of the actual array for the wKeyPosition sending it the number of elements in the array but not the actual data inside the array?. Is that right?
That would explain why when i was compiling it the white key would be like 50 px further away from where it was meant to be. This is all making sense now.
now i can build my key board YAY
Cheers