how can I restore Logic X files and other Audio (BIAB) and MIDI files that have been changed to Unix executable files by recent OSX updates?

I have been using a Mac since 1985 and have amassed over 30 years worth of material, and work that has been converted to unreadable Unix Executable files by recent OSX updates. Silly me, while I was recovering from open heart surgery I updated my Mac OS to Yosemite and now 30 years worth of work has gone missing. Does anyone out there have any idea how I might be able to recover my work. I have about a TB of ortginal scores, songs and scraps that I would like to get back to working on.

The files have been developed using a series of applications beginning with Performer on older Mac Systems (7,8, 9) Band In A Box (dating back to 1990), Pro Tools for Mac with System 9, Garageband since it came into being and Logic Studio 8. Any ideas?

please advise and help, and I may need some technology speak instruction

Lp