Shut off while driving will not run

I was driving down the road in my vehicle the other day an it shut off. Now won’t turn over. I’ve been having problems with it lately where it won’t start. Turn the key over an nothing. Then it will start out of nowhere. Now since it quit running yesterday when you attempt to start it it will try to turn over but nothing. I’m assuming it’s the something to do with the fuel pump but however could be as simple as the filter or relay I just don’t want to start buying random thing. And I don’t want to tear the bed off for no reason. An ideas to make it more of a simple checking process? Thanks in advance.