My GridVIew Is Not Work I Can'n Perform Edit and delete?

Question

I am using In my program gridview function but i can'n work

null refference are given please any body can help me for solve this error?

 

 my program file are there with db in txt file 

 

 

any One Have a Solution Then Give Me  I need Your Help Devlopers 

I am Student This task is used in my project please help me