Suzuki Alto not starts, No current

My car sometimes miss when I start. I am using duplicate keys, while original key also works. When it start missing, it will continuously miss. But still sometimes starts. Battery is new and charged properly. Last time I was in problem and I called the mechanics and he only disconnected the battery wires and reconnected them and then it starts easily. According to Mechanic problem is resolved, but I think disconnecting and reconnecting simply reset the car’s computer and problem will appear again soon. If it is anti-theft alarm problem, then why my car think that a thief is trying to start it. what should I do.

ok, you have a lot of information here, but not much that can help us figure this out.

Do you have a starting problem? If so- what happens when you turn the key to start?

Do you have an engine idles rough problem? if so, does the “Check Engine” light illuminate when this happens?

Do you trust your mechanic? if not, can you find another one? Has the original issue (s) returned after the battery was disconnected/reconnected? If not, how long ago was the battery reconnected (time and miles)

What engine? What year? How many miles?
You mention alarm- do you have an aftermarket alarm on this car? or some sort of factory security system?

I think he did more than just disconnect and reconnect the battery. He probably did that in order to clean the terminals. If your terminals are nice and clean right now, now white/greenish powdery accumulations around them, then that is what he did and you are good to go. He fixed your problem.

The fact that he didn’t take advantage of you by selling you unnecessary parts and repairs means he is likely a keeper (someone you want to do business with in the future).