when i go to the nether with my diamonds there was no ground under me just lava then i went back with nothing ground was back then i went back with iron no ground under me just lava

so i had all my diamond on and i went to the nether and there was no ground under me just lava i died with all my diamond i went back with no gear there was ground under me then i went back with iron stuff and no more ground under me what im asking is to get my diamonds backs with enchants and my netherite i dont have any files because its on my xbox and im on pc but pls help me