Chosen Solution

I downloaded Windows 10 then tried to go back but what happened is that it deleted every file including the booting files for it. Is there anyway I could get Windows 10 or 7 back or any way to make this work because I just bought this computer from a pawn shop.

If the Boot Files are missing you need to reinstall the system. However, you might loose all your data. However, booting to Windows Recovery from your windows installer disk and opening Command Prompt and entering fdisk /fixmbr might work.