Server Gone Missing

so i made a server and i spent lots of time working on it but then today i changed the server from vanilla 1.13 to spigot 12.2 in order to add some plugins etc but then the server wouldnt even start. so i turned it back to vanilla 1.13 and removed the plugin etc but when i launched up the world, it was a completely new world. ive tried uploading a backup, generating the world etc and nothing works. please help as i have spent hours on the world and would not want to go from scratch

dont worry, one of my backups worked. although i lost some progress, at least i didnt have to restart