If you have no water in your apartment this maybe due to one or two problems
No mains pressure coming into your apartment. The way to check this is to turn on your cold tap in the kitchen. If you have pressure in the cold tap and nowhere else then the problem is with your water booster pump.
If you turn on the cold water in your kitchen and you have no water then the problem is outside of your home. Check with your neighbors to see if they have the same problem as the mains has been turned off and check with your property management company or Irish Water and these can tell you what areas are affected.