More often than not starting issues a re simple problems, so check the basics before you look into looms potentially being in the wrong way etc.
Is the check engine light on? If the ECU is preventing the car from starting, it will most likely be on.
Coils plug in on harness with black connectors for rear cylinders and grey connectors for front, injectors plugs are also colour coded in the same way
Check the spark plugs are in good condition.
It also sounds as if you have had some work done to the car recently, it will pay to back track over what was done and rule out things being put together differently. For example if you have had an auto to manual transmission conversion, the wiring side of things may not have been done properly.