How do I fix this??? I unchecked the file from read only and still does this
What is the file extension of the file you are trying to inject?
Borderlands 2 save
I think he asked for the full file extension, e.g. like .bin, .txt, .jpeg, .RAR or .CON etc. 
I think we chatted about this through PM. If it’s the file you modded with Gibbed you can’t drag and drop it.
I’m not sure if you completely understood what I meant by “Replace” the file in your original save. With your original save open in Horizon click on the contents tab. Right click on the SaveGame.sav file like show in the pic below and choose “Replace”, locate your modified SaveGame.sav file that you modified with Gibbed and select it. Now "Save,Rehash & Resign it. Now it ready to moved back to your 360’s hard drive or load the save from your USB drive.
Different File not from Gibbed
It still may be only the SaveGame.sav file and not a full content package. Try what I suggested with a dummy save.
ok give me a min
If it doesn’t work please link us to where you downloaded the file from or tell us more about the file.
wont even let me use a none modded game save
What won’t? Horizon? If you have your own save(s) on your USB drive are you able to open them in Horizon?
yes but can’t drag and drop any others
You can’t drag & drop if you’re running Horizon as Administrator, but but that doesn’t appear to be your issue. I would recommend a fresh install of Horizon to see if that corrects it.