Before you start replacing derailleurs, I'd look for something else going on. A front derailleur doesn't suddenly stop working because you changed the cable. If anything it should have helped.

Also, front derailleurs don't generally just stop retracting unless there is something broken. I think you could take the front derailleur off the oldest crappiest Schwinn Varsity from the Salvation Army, and it would at least still have spring tension and probably work just fine.

What happens when you disconnect the cable? Can you move the derailleur by hand, and does it spring back to the inside position? If not, is it "stuck" or is it "loose" (no spring action)?