hi all, just wash my car and was going to go for a run out as it is sunny, but she wont start

noticed a faint humming noise coming from the back end yesterday morn while going to work and monday morning she took an extra couple of seconds to fire up on the key . now when i turn the key every thing happens but firing up . i have no lights staying on and all electrics seem to work. so wondering if its a fueling problem? cant smell any petrol under bonnet even after putting foot on gas pedal while turning the key to try and start her. it an auq engine, anybody any thoughts? i av got acsess to a code reader but 18mile away. so just wondering what it could be, any thoughts anybody ,thanks in advance.