"Launching the game failed!" error please help

[Reapers_Core]

Ok so I'm trying to download and launch Forge version 1.8.9 and I click on the Windows installer option and I download it and it works all the way into the mine craft launcher then I click play and it works up until about 19/30 megabytes downloaded and then this error pops up.

Here's the error:

 

Failed to download file, the file contents differ from what was expected.
Name: jopt-simple-4.6.jar
URL: https://libraries.minecraft.net/net/sf/jopt-simple/jopt-simple/4.6/jopt-simple-4.6.jar
Filename on disk: jopt-simple-4.6.jar
Path: C:\Users\*myname*\AppData\Roaming\.minecraft\libraries\net\sf\jopt-simple\jopt-simple\4.6\jopt-simple-4.6.jar
Exists: File

 

I don't know if the link as anything to do with it

How in the world do I fix it, I've uninstalled and reinstalled this stuff.
I've downloaded quite sketchy stuff and it still didn't work.
I've looked for 2 hours straight now on how to fix this and I've come up with nothing in the end.

Everything else works fine like Optifine and the normal game itself it's just Forge that won't work.

What exactly is the issue and how can I fix it?

Also I've uninstalled and completely removed my computer of the sketchy things I downloaded so those aren't a problem anymore.
From what I see, what 'I think' is the issue (which is probably wrong) is that it double checked the file that it was installing (jopt 4.6 thing) and it wasn't the correct file but idk how to get the correct file and idk what to do can anyone help please?
I'm doing all of this for the skyblock addons mod if anyone knows a better way please let me know

 

(if this isn't the correct place to post please direct me to the right place)

Edited December 6, 2019 by Reapers_Core

[Reapers_Core]

You know what I completely didn't read the EAQ before posting I just saw it I'm gonna go read it and see if it helps also idk how to delete posts I'm so sorry rip

Edit: read it, please tell me what I'm doing wrong when posting i've literally never done this before I just wanna get this fixed and idk how

Edited December 6, 2019 by Reapers_Core