My self hosted server had it's blocks corrupted

[Ruairi970]

i've been playing my hosted modded server, just advancing with mekanism and other mods in 1.12.2 and today i went back to it and when i got in all of the blocks were either changed or gone, for example my reactor casings were changed to dark steel anvils and my back wall was changed to nether brick, i managed to revert to a backup i made a day or 2 ago but i did lose about 12-14 hours of work, not looking for a solution necessarily, just very frustrated about the whole situation and wondered if anyone else has had such a thorough block corruption event, i'll attach pictures of the aftermath and the before pictures if i can find them, the before pictures are out of date too, i had upwards of 10000 iron ingots and over 2000 of every ore and the third picture is where all of my machinery used to be, quarry, me system etc