I replaced the fuel pump and filter.3rd time driving it would not start again.

What is your question?

Replaced fuel pump and filter, car started right up. I drove to the store put in more fuel. Started right up again, drove it home. Next day drove to store came out and car would not start. Over the next few days I attempted to start it with no success. Yesterday went outside car started right up. Has started each time after that. I'm scared to drive it, I can't afford to be towed again. What could it be? Your help would be greatly appreciated.