Clio won’t start, it sounds like electrically it is trying but won’t turn over

My Clio sport 197 just would not turn over this morning?
All was fine before!
Would it be the crankshaft position sensor?
Where is it located and how do you get to it, in all that madness
 
Do you mean you can hear something spinning but not the engine or something else? If it’s the former it will be the solenoid in the starter motor that has gone.