setting up disc brakes on a frame not made for disc breaks

[Deadguy]

My bike was stolen and i recently got it back... but some of the parts where switched out. They replaced my 27.5 inch forks with 26 inch shocks(pretty nice ones though) and my 27.5 single gear wheel with a 26 inch mtb wheel with a disc break disc on it. Finding a 27.5 has not been easy. And my breaks wont reach the 26 inch rim. I was thinking about ringing up some kind of extension to mount the break pads on.. then a friend said he had a disc break set up. But i dont have the mount holes on my fram for it.
Is there some kind of adapter i can mount on my frame to make it work with the disc breaks?

Any other ideas on how to rig breaks on it are appreciated! Thanks in advance!