Blinking Cursor on a Black Screen

[Joe Bennett]

Okay, so I'll start off by saying i have two separate HDDs...
The first I put Linux Mint XFCE on, about 3 months ago. It is a 1 TB Western Digital 7200 rpm Hard Drive. The Second I recently added Windows 10 to. It is a 80 GB (it's like 5 years old) Seagate 7200 rpm Hard Drive. 
Before I added Windows 10, my Linux Mint hard drive (which is brand new btw), was working and booting perfectly fine, however, when I added Windows to my other hard drive (which previously has Linux Elementary, which also booted just fine), I had no access to the other hard drive in the file manager, and I could find no way to mount to it. When I rebooted, and tried to boot into the Linux Mint hard drive, it came up with a black screen, with a blinking white cursor (underscore, or whatever you prefer... This "_"). Now I let this screen sit for over 10 minutes, but nothing. 
So here's what I've done... 
I ran linux on a live usb, and managed to open, and edit files in the hard drive, so I know my data is not lost. In fact, in a worst case scenario, I can simply copy all my files to an external hard drive, and only lose my software, settings and preferences, drivers, etc. However that is not at all optimal, but it's better than losing 2 years of hard work. So yeah, any ideas on how to get rid of the problem? 
 
(Note, this is not my image, but it is the same screen I'm getting...)

[Joe Bennett]

Still having the issue...