Renault laguna older model 2000; bought it when it was a year old,has never caused me any probs till the last two

Hi. Before you go any further, I would advise replacing the engine speed and position sensor (TDC), and the harness kit also as without this signal the engine will not start, and Renault vehicles along with many others can have problems with this sensor/connection. I personally have changed hundreds of these. It is relatively cheap to replace and takes about half an hour. I suggest getting the genuine Renault part and also ask for the harness kit that can be replaced which includes a new connector and a length of wire. It is located on the gearbox above the flywheel and in the top centre of the casing. It is located with two 10/11mm headed bolts. This would be my starting point so you can at least eliminate this common area. If you wish to try and disconnect it and reconnect it when it doesn't start next this may indicate if this is the problem if it starts straight away after doing this, but this is not always guaranteed. The best way to eliminate it is to replace it and retry. I hope this helps. Kind regards