As Ummmm has effectively suggested, you won't get a meaningful answer here unless you provide some more information:
What type of appliance? (Washing machine? Dishwasher? Something else?)
What type of noise? (Rattling? Rumbling? Whining? Whooshing? Humming? Knocking?)
Does the appliance otherwise work OK or, for example (if it's a dishwasher), are items coming out dirty or streaked?
How old is the appliance? ('Wear and tear' problems need to be considered if you've had it for ages but they can probably be discounted if you only bought it recently?)
There are lots of knowledgeable and helpful people on this site but, to the best of my knowledge, none of them are mind readers!
(Welcome to The Answerbank, BTW!)