Suddenly I’m having a hard time starting my car, once it starts it runs ok. What could be wrong?
Something is broken - or near to it.
How about you tell everyone what kind of car you have - year, make, model & mileage. Say something about its maintenance history.
And then describe what “hard time starting” means. You turn the key and…[you hear, feel, see, smell…]
Details, please. What you have described could be anything from you’ve lost your key to a serious engine mechanical problem. This is akin to going to your mechanic and saying “my car is in my driveway at home and is broken. How much will it cost to fix it?”
Also tell us if you’ve had the battery and charging system checked. They do this for free at many parts stores.
Does the engine turn over and not start or does it not turn over? If the engine doesn’t turn over the first thing to check is to see if the battery cable terminals, ground and connection at the starter are all clean and tight.