@Bad-Company-13 Unless someone puts a malware on that mod, which, if they do, it can't get on gta5-mods.com since rappo(site admin) is always working to approve mods which are safe. So fried PC = nope cant happen.
Talking about your GTA retail problem: you really can't mess up if you use the mods folder technique(which you must use in the retail version). Now that, and literally every other mod except for RAGEPluginHook requires dinput8.dll in your game directory. You want to play Online again - delete it. Wanna play modded? Put it back. I just have RAGEPluginHook in my directory as it doesn't do any harm, since you launch it in a different way.
And even if you do mess up, one way or another, you can use the command -verify, you can put it at the end of the "Target" in your shortcut or you can make a text file named commandline in your GTA 5 directory and enter in -verify. WITH THE MINUS SIGN!
Then the launcher will check if you have all the files installed, if you do, it'll let you play, if you don't or some files are "corrupted" (most of the time that means a mod is added to your vanilla RPFs), it'll download it and let you play.
OR, you know, you can make two folders like @LeeC2202 does. I don't know how he does it, so ask him