Sansa Fuse suddently not visible on my computers

I had the same problem several months ago.  At first, Fuze would show up briefly on computer, then disappear although Fuze screen still said “connected” with spinning wheel.  Then it wouldn’t show up at all.  Tried all the gyrations you described with no joy.  Another symptom was that Fuze would not charge battery.  I didn’t have a second unit to play “swap the cable” so I contacted SanDisk support by phone and described the problem.  They replaced Fuze with a complete new package (player, cable, earphones, software disk, manual) under warranty and they paid shipping both ways.  Why spend your money trying to fix their defective product?