First thing I check when I get  a service call for low water pressure is the condition of the water filter cartridges. Replacing the filter cartridges is an ongoing maintenance chore that if neglected will create low water pressure in your plumbing system. The cartridges clog up over time and need to be replaced as often as needed.  I replace my cartridges when I notice a drop in the water pressure as I’m showering. When the pressure gets so low that it bugs me it’s time to change them. I’d say about once a month is normal at my house. Your house may be less often than that. I replace both my sediment filter and charcoal filter at the same time.

No water at all to your house could mean the pump is out. Check the breaker and see that the pump is plugged in. The pump not turning on could be a bad pressure switch if you determined that electricity is getting to the switch.