I cant upload or delete files!

I run a Garry's Mod server.
And I edited a file addentities.lua
And now I want to reuload it
But when I try to delete it
It says Error: Connection timed out
And if I try to overwrite it it says Error: Critical file transfer error
When I look at the file it says Filesize: 0
Its like the file is nothing
What do I do??