MP3 songs lost after DMM transfer to my Philips center

After the MP3 songs are transferred from the PC to the Music Center via DMM, please DO NOT disconnect the power cord. The Center is updating its internal database to make the changes to the music library. Please wait for around 20 minutes to let the Center update the database completely. When the internal updating is complete, you will be allowed to set the Center to ECO Standby mode. To go to ECO Standby mode, please press and hold the STANDBY-ON button on the Center for 3 seconds. The display of the Center will then be blank and without any message on it.