why are firewire connections not working?

I have a 2009 iMac and have been using numerous external HD's using both Firewire 400-800 ports to transfer data.

I cannot recall what update I did, whether it was for Mavericks or Yosemite but after one of those updates my Firewire ports stopped working.

I have tried resetting the SMC, repairing discs through the utilities, just anything I could do to get my drives to recognize the discs, no luck.

Has Apple just done away with Firewire and do not support the drivers any longer? I know they are all about Thunderbolt and USB 3.0 but I can't see the logic in just abandoning Firewire unless they have deemed my PC an antique. Which I know has been labeled as such, but it still performs great and does what I need it to do. I can use USB 2.0 to transfer files on some of my drives, but two of my Lacie drives do not have any USB ports and I cannot access any information.

Can someone give me a definitive answer as to what's going on? I have done numerous searches on this subject and nobody gives an absolute answer.

There has to be an Apple guru that knows the reasoning behind this, and is there any way to get around this problem...a fix?

Much Appreciated.