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Hi @Anonymous ,
FILLMODE system variable in your drawing is set to 0 (zero), so you cannot see hatches in it.
You need to set it to 1:
At the command prompt type FILLMODE and hit Return, then type 1 and hit Return again:
Command: FILLMODE
Enter new value for FILLMODE <0>: 1
Command:
Now try to use HATCH command.
There are also many things in your drawing that you may not need:
1/ view direction is not parallel to XY plane of the current coordinate system - as a result the hatch you create will be displaced from the correct position:

2/ you can set the correct view direction with PLAN command, but your drawing has a lot of objects that I think are not related to your current task, and these objects are scattered far apart from each other. So if you will try to use PLAN command the visible contents in the drawing area will change to show all these objects:
This is what you will see:

If you don't need these additional objects, you have to delete them.
3/ current object transparency in your drawing is 75 (the default value is 0):

Do you need this? If not, you need to set it to 0.
4/ The objects you are working on currently have different elevation. if you look at them in 3D view, you will see this:

Therefore, you need to flatten this part of the drawing, for example, using the FLATTEN command.