Engine does not start

Last October, my car did not start and was towed to Midas. Was told the starter was bad. Bought one from auto parts and had Midas installed for me. Despite some initial difficult, it worked. I drove on short trips on weekends only. Last weekend it was find, but this Saturday, after sitting for one week. the engine would not start. It cranks but there was no ignition.

What I fear most is the worn-out of the part of the engine that engages the starter. No enough power. Is that possible? Or is the problem with fuel system and electric system?

If it cranks it’s not the starter.
Spark and fuel pressure are the next things to check.