will not sew backwards

Congratulations!

My first thought is that it needs a thorough cleaning and proper lubrication. If it's been "oiled" with something like WD-40, the lubrication may be entirely evaporated and the linkage that allows reverse is now frozen. If it's been oiled with something like 3-in-1 type household oils, the oil may have gotten gummy and stopped the reverse action.

If it's an older machine, out of warranty (and I suspect it is), then you might want to consider joining the yahoo group "wefixit" and learning how to clean and oil and adjust this machine yourself. If it's a newer machine or you're not fascinated with mechanics, take it in to your repair shop. Around me, in the PNW US, a COA runs $50-120, depending on the complexity of the machine.

Kay

Same thing happened to me!!!