Unintentionally reinstalled while transferring the game file onto a new drive.
I recently got a new hard drive and was moving things back and forth through it to free up space on my original drive. I had moved the Epic Games folder onto the new drive, which had made the launcher assume that I had deleted the game from the original location, and made me redownload it. Now, I have it downloaded, I also have the old copy, which has the mods and edits to the files. Can I just replace everything in the new download with my old copy?
@NateTheNinja21 As you found out, in general, you don't move apps from one drive to the other. You need to reinstall unless they are what you call portable apps. An exception would be if your drive has exactly the same path (i.e. it was drive C and still is drive C) and even then it's not 100% certain as software might be looking for a drive ID or other characteristics.
Now can you use the mods from the old copy to the new copy? Absolutely. Just copy over your mods and scripts folder to the new installation. Also copy over asi files such as your trainer, heap, pack, etc. to the root folder of the new drive or install them with new up to date copies. This assumes of course you are using the same updated version of GTA5 on the new drive as you did on the old drive. Mods use relative paths so they don't care where you install them as long as they are in the same folder as GTA5.exe.
You will also need to transfer any customizations, screenshots, user music, or saved games to the documents/rockstar folder or steam/epic user folders.
OpenIV however will likely need to be reinstalled as it isn't portable and it will search for your product key and new game folder if the path changed. If you had any specific OpenIV customizationss such as favs you can copy them over from the old drive.
Also if you had any .exe tools or mod scripts that aren't portable (i.e they have windows installers or uninstallers) you might have to reinstall them as well.
The only exceptions I can think of, and I don't think it would apply to your case, is if you had your own customizations that had an absolute reference. For example it pointed to drive c and now you are on drive p - but that is very unlikely. All mods you download will use relative references as will OpenIV, once installed, based on the root folder.