It's one of the major issues and happens a lot. Best option I've found is regular backup on metadata.nostr.com

nostr:nevent1qqsxg2daj7f6h8sjyjx7354gtuyq6t3nx9h2432jz8n405ke32snksgpz3mhxue69uhk6mmrdd5kuemeda6jucm0d5pzpdhp8xva5zwelv475mwlttr9dy7kdlayxuuwqzd2cm2500jl60yqqvzqqqqqqyq738r7