pranav2016:
<time.h> library is helpless. i tried that one earlier
I have no idea what library that is.
The "Time" library is very useful i.e. <Time.h>
The key is to track time using epoch based time values not "human" or "wall clock" type of time that you are using.
If using epoch based time values you can get something like the time in seconds (which is what Time uses as well as pretty much any mainstream OS to track time internall)
Then to tell how much time has elapsed you do simple subtraction.
The key is stop thinking of human/"wall clock" type time and use epoch based time values.
And then convert from an epoch value to a human time only when necessary.
BTW, the Time library also has a companion TimeAlarms library that can help doing the type of interval or repeated alarms like you have mentioned.
--- bill