1. What kind of car do you have? (Make, Model, Year)
2. What exactly happens when you try to start it?
* Does the engine crank (turn over) but not start?
* Is there a clicking sound?
* Does the dashboard show any warning lights?
* Do you hear any other sounds when you turn the key?
3. What have you already tried?
* Have you checked the battery?
* Have you tried jump starting the car?
* Have you checked the fuel level?
* Have you checked the fuses?
4. Any other relevant details?
* How long has the problem been going on?
* Was there anything unusual happening before the car stopped working?
Once I have this information, I can offer some potential solutions and steps you can take to troubleshoot the issue.
Please note: If you are not comfortable working on your car, it's always best to take it to a qualified mechanic.