A method for accessing a non volatile memory device including at least one group or sector of memory cells divided into regions programmable with two different data storage densities and accessible with at least two reading modes, for example a two-level mode and a multilevel mode. The memory regions are being organized into pages including a sub-group of memory cells for storing error correction codes of the data stored in the multilevel mode. The method includes providing at the beginning of each page at least one first cell wherein the information concerning the ECC protection or not of the whole page is to be stored. In the sub-group of cells at least one second cell intended for the storage of information concerning the programmed or erased state of the same page is provided. The content of the first and of the second cell is read before accessing, in programming, the corresponding page of the memory region.