yes they found my diploma certificate fraudulent
Good.
Did they give you an opportunity to respond to the fraud allegation? Because normally, they should ask you to respond to their findings. But be that as it may, now that your certificate is found to be genuine, i will advice you contact a lawyer to officially write to IRCC explaining the situation and how they erred in their initial decision. This might be a bit costly but will be worth it!
This procedure will reverse the 5yr ban (very important step) before you put in another application. If not, you will be wasting money for applying over and over again with no positive response
Also remember, a ban is a serious thing. Even after the 5yrs, it will still be difficult to get any entry visa into Canada. They may still see you as a fraudster eventhough the 5yrs is over ( this is just an opinion, not 100% certain)