4gb sandisk mp3

can anybody help me my mp3 will not format i cannot put all chapters of my audio book on to it/  ikeeps saying sychronize to continue your music subs and i cant get rid of this i am a senior i have tried everything i am at my wits end

hi no i have never had any music on mp3 only audio books i did buy it off ebay it might have been used

thank you for your reply i did clear it and when i used it on overdrive media console it came up  again so i  cleared it and tryed windows media player and all chapters went on so its media console thats the thouble so it looks as  though i wont be able to use it on media console  thanks again for your help m menday