Why would reverse suddenly stop working?92 accord auto.

 

Because something is broken?...lol

Will it physically shift into reverse and it's just not working or does not not go into reverse at all? You could also check for codes, is the D4 light flashing/on?

Start with the obvious. Check your shifter cable and linkage and check for stored codes on the ECU/TCU. It could be a shift solenoids gone bad. If There are no codes stored, the solenoids have checked out and it's nothing outside of the case then it would be something inside of the case that has failed.

 

Still driving my 98 Accord Coupe, V6 automatic. Has 127,000 miles on it and one HUGE fault: I'm on my 4th transmission!

 

That's a well known issue for that gen V6 autotragic transmission. Not usually as much of an issue with the 4 cylinder automatic transmissions.

 

Does D1 still work?
When was the last time any service work was done on the transmission?
Blinking D4 light? Does the D4 light work?
B7XA shitbox is nowhere near the equivalent of the rock solid H4A.

If you are on your fourth would you state what the previous issues have been when the trans dies? Well known issues are crap differential bearings, 3rd gear bearing/clutched burning up, and its suicidal tendencies thanks to a faulty PRV that jams causing overheating and cooking of the torque converter, fluid, and killing the trans in short order.