It sounds like you did a "Subject To," where you deeded the property to the investor but the mortgage stayed in your name. The investor, in turn, promised to pay your mortgage and, at some point, refinance the mortgage.
If that's the case, then you've got real problems. You no longer own the home, but you're still on the hook for the mortgage. And if that's the case, you can't put the house on the market.
I'm guessing the investor ran out of money. He/she likely would be willing to deed it back to you . . . but you'd still have the past-due mortgage amount. However . . . you haven't been paying the mortgage on the property for the past 5 or so months, so you hopefully have some of that money saved.
You certainly should contact a lawyer. But, please, make sure it's one who understands real estate investing techniques. Most don't. I'm not a lawyer, so this isn't legal advice. But my approach might be to twist the investor's arm to get the house deeded back to you. Meanwhile (with your lawyer's guidance or assistance), contact the mortgage company and try for a loan modification. Pay what arrearages you can, and try to have the remainder tacked on to the end of your mortgage. Otherwise, try for a short sale. The worst-case scenario would be a foreclosure.
And because I'm in your area (Northern Virginia), you might drop me a line. I'm curious who the investor is; I know some of them.
Hope that helps.