Our outside outlet that was previously working, decided to stop working the other day (there's not that many Christmas lights plugged in). It has also effected the outlets (not lights) in all 3 bathrooms as well as the sunroom. We have 2 outlets in the kitchen that are GFI--and neither were tripped, but we reset them. There isn't a breaker thrown in the box either, although we reset those as well. My husband replaced the outlet last night, but still nothing. Does anyone have any suggestions, or do I need to contact an electrican to come out? Thanks so much for any input

Trouble shooting this is more than just replacing parts. A voltage tester is needed, and knowledge of where to find a possible, and most likely, loose connection.

If you have the tools and knowledge, then this may be something you can tackle yourself, otherwise, hiring a good service electrician may be in order.

This problem is probably fairly simple to solve. By electrical code outlets in potentially wet areas are required to be protected by a GFCI circuit protector. I am sure you can read up on exactly how they work but essentially they are a device that detects a ground fault (or short in the system) and automatically trips the breaker to protect your life and property. All outlets near bathroom sinks or tubs, kitchen sinks, laundry tubs and outside need to be protected. GFCI Devices come in a variety of types and sizes. For economy reasons often an electrician will buy one or two GFCI breakers for the whole house rather than get individual units for each outlet. THAT is why your outside outlet is connected to your bathrooms. Since the problem occurred recently I would guess that there is a problem with the device you most recently attached.(the christmas lights) begin troubleshooting by doing the following.

Step 1 unplug all exterior Christmas lights and all appliances plugged in to any outlet that has been affected by the problem.
Step 2 Locate your breaker box and determine if breaker is tripped.
Step 3 if tripped Reset breaker and check bathroom outlets for electricity. (use a hairdryer or other small appliance that you know works well)
Step 4 if outlets in bathrooms work - -check outside outlet with same appliance (make sure you are standing in a dry area and the outside outlet looks good no char or black marks no water etc) IF the outlet now works the problem is in the christmas lights (probably just one strand)(if outlets don't work skip to step 6)
Step 5 determine which strand has the problem by using a good outside extension chord and plugging in one strand at a time. Once found replace or repair the strand.
Step 6 if all outlets still don't work the lights may have caused the GFCI to fail permanently. You will need an electrician to repair the problem

For all its length, the above post leaves out the essential step of tracking down any GFCI outlet and reseting it. While a GFCI outlet may fail, replacing one requires little more than any other outlet. You do need to attend to reconnecting the same wire to line and load.

As tkrussell said, you need some basic tools and knowledge, or to call and electrician. At one time, none of us had any tools and knowledge. The tools are easy.

To do simple checks like this you do need some tools. A test light, a meter, or a voltage detector might be the best place to start with. I came across the niftiest gadget for trouble shooting, a voltage detector. They work through the insulation of wires. There are several brands. I have a GB Instruments GVD-505A, less than $15 at Home Depot. Touch it to a hot wire, and the end glows red. Find the doodad that lights it on one side, and not the other, and you have the culprit. You do not have to open up housings and expose electrical contacts. You are looking at where your hand is, not where the meter is. Most people are capable of doing repairs and will get it going and not get hurt if they use a little sense. The voltage detector makes it even easier.

Since the problem resulted in outlets in multiple areas being out it is not likely that a single GFCI outlet is the offender but rather the Breaker is the GFCI type. Resetting the breaker would also reset the GFCI if it is in the breaker.