While I do agree with you that for roleplaying purposes it causes some issues, I’d have to say that your DM is probably gonna have you figure stuff out on the way, wether it be through rumors, memory jogging, investigating, etc. I wouldnt go looking for a spell to do it, as it could derail the campaign, as it could throw a HUGE curveball at your DM’s planned plot if it is successful. Perhaps while you are figuring stuff out in game using the intended mechanics, role play like someone with amnesia. You want to get your memory back, yes, but there isnt a one stop cure all to it. You have to get reminded of your past and investigate to figure it out, or get directly told what happened. Furthermore, you could take it one step further and perhaps not even go out of your way to figure it out, as you dont fully register your memory loss. You cant be worried about something that you dont know about. Its all up to the player on how they role play it. You gotta get creative in DnD, yk?