used one address multiple times

I am new to bitcoin and multibit and wasnt aware that i am not supposed to use an address more than once but i did and now i am not receiving my payments.is there any way i could fix this?? please!!

You can use an address if you want to, it's not quite so secure as using a new address every time.
If you are not receiving payments to an address that is in your wallet then it's some other problem, like the payment not being sent or similiar.