1. Did you purchase the land through any registered Sale Deed?
2. If yes, did you collect the original Title Deed of the seller from him while purchasing the property from him?
3. If yes, then he can not create any mortgage of the property since for creating mortgage, original title deed is required to be deposited with the mortgagee,
4. If the said Title Deed has not been given to you then ask the person claiming to be the mortgagee to show you the original Title Deed to establish his claim,
5. If the original title deed is found to be with him, file a cheating case against the seller.