No power/lights in part of our garage
Ok so now we are in a troubleshooting situation. The first thing everyone is going to ask is if the circuit(s) not working are on either a GFCI or AFCI/GFCI protected circuit or if there is a tripped breaker. Depending on the age of you residence this could be inside the panel as a breaker or on a protective device and it could be located almost anywhere. The reasoning is that this is around 85% devices in the garage are not working.

If it is not a tripped GFCI or AFCI/GFCI breaker or device the second cause is usually a loose or broken circuit. So you need to trace it out. To do that you must identify the circuit. You will either need a circuit tracer (a fairly expensive piece of equipment) or a multimeter/ammeter (not so expensive, somewhere around $45.00 maybe even less). If you don't have any of these meters I suggest you get one or have someone else troubleshoot it.

If you have a non contact voltage tester check to see if you can find power by stabbing it in the small slot of the receptacles. If you get a ring at a device not working that is usually where the problem is. 

If that doesn't work you start by opening up the boxes. Be careful we don't know if there is any hot wires in the boxes since we don't know the circuit and we can't shut off the breaker. As you are opening the boxes look for a dislocated conductor and if you have a non contact voltage meter test to see if there is any power in the box. What we are really trying to to find the is end of the circuit. That would be the box with only one feed in and no feed out (basically three wire a hot, neutral and ground). Then we can work our way back to the problem. If the problem is not in any of the boxes that are not working try going around the garage and find the circuit that leads to the device not working. Try and determine which box is closest, it should be a box between the device not working and the breaker panel. 

Once you do find the broken or loose conductor go through the breakers and find the circuit. If the panel is not labeled you will have to turn each one off and on until you do not get a ring with you non contact tester.

Then and only then should you make the repair, then turn the circuit back on and test to see if the devices are working. Then turn the circuit back off and button up the devices and turn the circuit back on. Test all devices to make sure everything is working correct.

Needles to say trouble shooting is very laborious and frustrating to the not so familiar and you may decide it would be worth bringing someone in who has the proper equipment and has trouble shooting skills developed by a ton of experience.

So I will leave you with this piece of advice. Before trying to troubleshoot, I would make sure that it is not a tripped breaker,GFCI or AFCI device. I would check it at least twice and even then go through it on last time before I did anything else.

Good luck