Auto deleting songs we wanted there argghhhhh!

Question

Our problem is when my husband deletes songs he's already loaded into the mp3 from his pc..... then reattaches the mp3 later to add new songs..... the pc starts deleting any and all songs that are no longer stored in the pc. HELP! PLEASE. There is some problem with syncing? Hours of work and tons of songs loaded are now gone, history! Frustrating! Is there a way to load songs onto the mp3 without using the sync feature?