Basically about a week ago, someone had gotten into my account due to my poor password choice as a child. After fortifying my account, having my skin changed, and a Mojang employee under the name "Nasim" helped me reclaim my username, I hopped back onto Minecraft. My username was still stuck as the foreign name in which I just took as an error of my username being changed by force instead of after the 30 day period. And so I just logged back into Minecraft again which deleted the previous username and replaced it with my own. Once all was well, I launched Minecraft 1.12 this noon, but it gave me this error:

Message: _ERROR
Unable to save download. la_la.lang_

Details:
_Name: la_la.lang
URL: http://resources.download.minecraft.net/3f/3f387a3d7c5903b81ebfe4204d09e29fd1d3b4ac
Error details: Attempting to move successful download to C:/Users\Griffin M. Bowling\AppData\Roaming\.minecraft\assets\objects\3f/3f387a3d7c5903b81ebfe4204d09e29fd1d3b4ac The process cannot access the file because it is being used by another process
Filename on disk: 440a-d102-013f-00eb
Path: C:\Users\GRIFFI~1.BOW\AppData\Local\Temp\440a-d102-013f-00eb
Exists: file_

What I got out of it was that Minecraft was creating a file location of some sort for the download to be installed, (even though I had already recently played 1.12) but whenever it was created, a separate file entity of some sort on a separate user (note that my username location on the save download was Griffin M. Bowling, while the overridden process location was under the username GRIFFI~1.BOW) would take its place before the download could be done.

I personally tried to fish into my files and try to delete the file that was overriding my download. When searching for the file, I found nothing but I did find a file that had the save contexts as the error: a sixteen digit file with four digits in four separate digit combinations separated with a dash each time. I experimented with the error message and found that every time I tried to download, it generated a new file location and "conveniently" and new entity file to override the download. My conclusion was that maybe the file I found was rapidly generating a new name to match the generation of the save downloads. So I tried deleting the file named "e7ca-9b85-757f-08ab" in which had no effect on the error. (So I quickly put it back in my files hoping I didn't screw something up)

I have NO clue what is causing the error and therefore have NO clue how to fix it. And I haven't found any past bug reports similar to it. So with a very sincere tone in my voice as I type this out, I ask: PLEASE HELP!!!