So after redownloading and re-extracting both DF and the LNP to a separate folder for a third time, DF still will not open. It will give me a security warning message asking if I want to run the program. After clicking yes, the game just won't open. I'm at a loss as to what is happening, since just a few days ago the game was working fine.
Nothing else on your machine is refusing to run, right? Because, if you're getting a security warning when you try to run
Dwarf Fortress.exe then you may have problems that have nothing to do with DF itself. Short of permissions being set ridiculously high, I've never seen that happen. So first thing, if I were you, is to just check to make sure an unrelated windows update or security software update hasn't screwed with your windows security settings and permissions. If you don't do it regularly already, give your system a malware/virus scan just to be sure. If all's ok and set properly, try running it in admin mode.
If it still does not work, you should verify that you've actually got everything extracted properly - i.e. nothing is missing from the folder. Could be a problem with your unpacker, corrupting data or just not pulling it all out of the .zip file. You should have:
If you don't, something is not working with the extraction.
If that's all good - your machine is cursed, apply holy water and/or a sledgehammer.
No, don't do that.