I am a renter but I have lost my rental agreement contract . How can i retrieve it?

The only party who would have it would be your landlord. If you need or want a new copy, you will have to ask him or her. Note that the landlord is not under a legal obligation to provide you a copy--it's hard to imagine why they wouldn't, but they technically do not need to. However, if they try to impose any conditions or costs on you that you do not remember from the agreement, you have a right to require them to show you the contractual (lease) term supporting the condition or cost before you comply.