Question about professional experience on resume please help?

okay so here goes nothing ...ive been with my current employer for four years and the first 3 years i was given the most experience i could ever ask for...but my superior who knew all the work i have done and my experience has left the company and ive lost contact with him. the superiors now dont give me a shot so im looking to find another job. but i want my resume to state all my accomplishments but im afraid. if they contact my new superior there not going to what ive done and there going to think im lying. what do i do?