If you are the owner of the Minecraft server and have access to the server files, you can find the seed of your world in the "level.dat" file. Here's how to locate the file:
Log in to your server hosting account and access your server files.
Navigate to the folder where your world is saved. This folder should be named after your world's name.
Look for a file named "level.dat" and download it to your computer.
Install a program that can open NBT files, such as NBTExplorer or MCC Toolchest.
Open the "level.dat" file in the program and navigate to the "Data" section.
Look for the "RandomSeed" field, which will contain the seed for your world.
Note that accessing your server files may require specific permissions from your hosting provider or server administrator, and modifying any files without proper knowledge or understanding can cause damage to your server.