launching the game failed

[marsha]

how to fix this and what does this mean?

 

I'm trying to install 1.7.10. When I try to launch mod I get this error message. Please help. How do fix this?

Is a mods folder supposed to be created when installing this mod? There is no mods file.

Failed to download file, the file contents differ from what was expected.
Name: jopt-simple-4.5.jar
URL: https://libraries.minecraft.net/net/sf/jopt-simple/jopt-simple/4.5/jopt-simple-4.5.jar
Filename on disk: jopt-simple-4.5.jar
Path: C:\Users\nicol\AppData\Roaming\.minecraft\libraries\net\sf\jopt-simple\jopt-simple\4.5\jopt-simple-4.5.jar
Exists: File

Edited December 26, 2019 by marsha
More info added