If you desire good answer on this forum then you must do your best to provide details. It would help if you would actually describe what you've done to diagnose anything so far. Also, please elaborate on what occurs when you attempt to start it.
- Is it manual or automatic?
- Have you inspected or changed the spark plugs, wires, distributor cap & rotor?
- Is it trying to turn over slowly or is it sounding normal but just taking too long?
- Did you mean to state that its idling high AND idling rough? Civic shouldnt be idling at around 1000rpms. You may need to adjust the idle.
- Is the idle surging while running or just in neutral?
Also, did you buy the car without driving it or inspecting it? No one should buy a car while blindly believing the seller.