a big issue came in my mind today after heard a conversation between two people regarding the H1B visa.

I used to work in the Gas station (owned by American) for the last 4 years and  got the pay check which was supposed to be illegal ( i know but had no choice) and now its time for me to change my F1 status to H1. Though after hearing their conversation, i found that it will be pretty much hard to get H1 visa because of my previous working status which i was not supposed to? so please help me out on this situation with your personal experiences and thoughts.

Thank you.