1. A decoding method comprising: performing a first decoding method comprising updating a plurality of variable nodes and a plurality of check nodes using probability values of received data; and performing a second decoding method when decoding of the first decoding method fails, wherein the second decoding method comprises: selecting at least one variable node from among the plurality of variable nodes; correcting probability values of data received in the selected at least one variable node; updating the variable nodes and the check nodes using the corrected probability values; and determining whether decoding of the second decoding method is successful.