Rekordbox 4.1.1 Cant't load song , lost hot cue,

Without any detail no one would be able to help you. You didn't even mention if you're on windows or mac!

error messages and a description of what you did and your settings in RB may also help

and see this: https://forums.pioneerdj.com/hc/es/community/posts/206610706-REKORDBOX-DJ-4-1-UPDATE-ERASED-CUES-COLOR-AND-SONGS-INFO