I think my teeth where nance appliance is hooked on has chipped/ broke because i often hear crack sound whenever i bite my teeth together. any advice?

Dentist: The earlier your dentist takes a look the better the chances or repairing what could be broken or cracked. Please see your dentist /orthodontist

Go to the dentist: Whoever placed the Nance needs to evaluate it. If not available, then find a referral from the source of the appliance. The sound may be a loose appliance which needs treatment.