My first post, will come back if problem not solved.
Symptoms: Replaced battery, cranked, sometime combustion, yes fuel NO START(solution at bottom)
My 1997 4.0 Discovery remained in my driveway for the last three months.
Old history - I left my lights on various times until I killed my battery, it wouldn't charge any more.
Bare with me.......
History: I replaced my battery and worked fine for months.
Slowly but surely it would not start right off the get-go over six months. I had to crank it and on the third or fourth crank it would start. Once it started, I rev-up the engine and go. As time went on I cranked it up to 20 minutes before it would turn on. Sometime it turned on but even when I stepped on gas it would die on me. I would end up discharging battery from time to time from cranking it to start, would recharge or jump start and would help. Mechanic said it sounded like the air flow (not enough air maybe). I went for a run one day and it cranked for two hours, no go, and towed it home.
---What I did after reading every thread on "won't start" and " replaced battery won't start" and talked to mechanic. ( by the way I'm a college student, no money for taking to shop, not a mechanic by any means)
=Replaced air filter $$$ (no difference)
=Replaced fuel filter $ (no difference)
=No codes
Once in drive way
Cranked (turned over no start) combustion once or twice. Started for three seconds once every three days.
=no codes
=charged battery (both in hood and outside/disconnected from Vehicule<-- which is recommended)
=Replace sparked plugs (one by one, did not want to cross wires)
=All spark plugs had spark
=Gas was getting to injectors
=Replaced CPS (Crankshaft position sensor) $40 (no difference)
=Replaced Camshaft position sensor $junk yard (no difference)
=Cleaned air intake
=Used starting fluid - No combuston
=Tried jump starting with a truck - nothing
=Tried to jump start with "jump starting charger" - nothing (what I used to jump the discovery when I drained the battery before)
=Added fuel and fuel injector cleaner fluid (no difference)
=replaced MAS (master air flow sensor) - nothing
=Checked battery leads (no difference) all lights and electrical worked
=checked fuses
=Checked battery charge multiple times
=Tried resetting alarm system (no difference)
= I tried everything I could think of and kept reading threads

I saved enough money to have a mechanic look at it to atleast diagnose it.
I decided to check the ignition coil as someone suggested and to check the V8 ignition diagram.
I charged the battery, disarmed the alarm. I tried to start it again twice (just in case) and it combusted for a second each time - no luck.
I walked my finger through the ignition wires from coil to spark plug. THERE WAS THE PROBLEM!!!!!!!!!! # 4 AND 6 WERE SWITCHED !@##%$#%$#%#$!. I tripled check with the RAVE diagram. switched them.... prayed ....and started it up. BEST SOUND I HAD HEARD IN MONTHS. I then remembered that I had a "reliable cheap family mechanic" change the spark plugs, wires, some block gaskets, change oil....a year ago. He moved away soon after looking for work (not mechanic related). He probably would have found his mistake months ago.
This is a long post because it was a long frustrating problem for me. No clear solution, with no exact date of malfunction, no codes and since I relied on someone more qualified than me to work on Discovery(I figured wiring was correct). I don't know how it ran for so long with no codes and having # 4 & 6 switched.

Hope this helps someone, somehow.

Solution:
Check V8 ignition diagram (This could have been the solution to a thread from 2009 who took Discovery to three mechanics/dealer and did not figure out solution, but after assembled back together the engine started right up)