@Adibordoy: Please can you confirm your device's model number and current Android version and I will look into this for you. How many alarms do you have active on the device? Is it then same ones that keep failing or is it random?
I'm not sure what could be going wrong here. When setting an alarm please ensure that you set the preferred day or date for the alarm to go off. Clock > Alarm > Tap '+' to add an alarm >Tap the days of the week you want it to go off. Set an Alarm Sound and Vibration type and you should be good to go. I would avoid selecting a date for the alarm to sound (via the calendar symbol) as this may restrict it from going off in the future.