I have a problem with my Defender Td5. The car couldn't be started, I had the ECU and Injector serviced then it started for 3 days but I hadn't had time to use it then the car died again, I checked all the engine parts and the electrical parts too but there was no failure or damage whatsoever, then I scanned but nothing If any system problems arise, please provide assistance and explanation. Thank You.

Is your battery fully charged, it needs to be to get a TD5 started especially in this cold weather,
Also try resetting the inertia switch under the bonnet, mine tripped once and engine would not start, I pressed the reset button and it fired straight up.