Disbale windows Key

Question

hi every one

if you can help plz dont hesitate  to give me answer would help me

 

i m working on exam project using windows form c# 

almost done but i need to lock key board and special keys like windows and alt anf F1,2..etc

so i tried many function none get me solution 

i tried key down press but its not working without fn key

so how can i disable this also

 

wating you guys 

my best regards