1. As mentioned, a GFCI may be tripped in that circuit. Reset the GFCI. If it still trips, unplug all appliances from the outlets in the circuit, then reset again. It may be a defective GFCI.
2. The cable from the CB usually goes to an outlet then another cable goes from that outlet to the next outlet and so on to the last outlet. Along the way you may have a box that feeds a light switch. Turn OFF THE MAIN POWER SWITCH!
Now remove the outlet cover, pull out the outlet and check for terminal screw tightness for the wires comming in and the wires going out. You might have a bundle of white wires twisted together (Neutral). They sometimes are loose. Do this to all your outlets on this circuit.
NOTE! This is dangerous work. If you're not comfortable with working on electricity, call an electrician. They have tools to track the circuit. They'll fix it in 30 minutes... Adios... Jasper