GFIs are required by the electrical code for receptacles in bathrooms, kitchen receptacles, some outside receptacles, and receptacles near swimming pools.
Ground Fault Interrupters are designed to protect from electrical shock by interrupting a circuit when there is a difference in the currents of the hot & neutral wires.
About every month or so you should consider testing your GFI outlets to make sure they function properly. First make sure it’s on and then press the test button. If the GFI works properly then appliance or electrical device should lose power and turn off, and the reset button on the GFI outlet should pop out, indicating the power is out. If the reset button pops out but the light does not go out, the GFCI has been improperly wired.
Common issues for losing power to your circuit attached to your GFI is loose connections on that line. Outlets located in the next room maybe causing the whole line to go dead or trip the GFI. If your having any issues you don’t want to take on yourself, please make sure to consult a local electrician for the safety of you and your family.