Buy a multi meter, (simple one costs 300-400Rs) and try to check voltage of battery in the morning before starting, if its in range of (12.6-13.something) battery is fine and there might be other issues in wiring. Once car gets started, again check the battery voltage when car is started in the same way, this will now show you alternator(generator's) voltage that must be (14.2-14.7), if not in this range, your alternator is either under charging or over charging your battery and thus damaging it. One more thing that when you check started car's voltage, turn all the auxiliaries on like head lights, stereo etc and then check alternator's voltage at the battery.
PRECAUTIONS:
1. connect the terminal correctly while using multi meter.
2. be careful because after all its BIJLI so......
3. set the voltage range on multi meter at 20V(DC) as it is next higher than 12V and 14V that you are measuring.
In this way you can check your,
1. battery's condition.
2. alternator's condition.
If both are fine, there might be some issue with:
1. wiring
2. fuel pump
3. self starter.
I would suggest research further on internet and diagnose the problem yourself as this can happen again and road side mechanics will not let you know the problem because your problems keep putting money in their pockets.