What are the reasons for a BMW suddenly not responding when starting?

[Nicole]

Failure to start may be due to reasons in the fuel supply system, starting device issues, insufficient cylinder compression pressure, or inadequate air intake. Reasons in the fuel supply system: Blockage in the low-pressure fuel line, loose pipes causing fuel leakage, air in the high-pressure fuel line, poor technical condition of the injector, incorrect injection timing angle, spark plugs failing to ignite normally due to damage or lack of regular replacement. Reasons in the starting device: Power supply failure, poor contact in the electromagnetic switch, poor contact between the starter motor commutator and brushes, clutch slippage in the starter transmission mechanism, cylinder head gasket damage causing air leakage, valves not sealing tightly leading to air leakage, wear in piston cylinder liners causing air leakage, or blockage in the air filter element.