My friend deleted something I owned in Mnecraft
You cannot get it back unless you have some sort of backup file of this world. if it is an online server they may have a mod with an "undo" or "recycle bin" feature that will allow you to access those lost items. Being that you are playing on the Switch it is most likely that your only chance would be if you had a backup file from manual or auto save. If not then the items would be gone.