Nostr sucks at saving notes long term and nostr apps don't warn users. It's one of those ways nostr is currently designed to keep the internet money-controlled and dysfunctional.
If the notes are still around on some relay out there, you might still be able to find them with this tool by nostr:npub1cmmswlckn82se7f2jeftl6ll4szlc6zzh8hrjyyfm9vm3t2afr7svqlr6f