"We removed a ceiling light and replaced it with a ceiling fan brace."

Who is we? You and the electrician? You alone? If it's you alone, rehire the electrician. If it's the electrician, then get a new electrician.

My husband replaced it. He has replaced lights and fans many times. It's three wires. How can three wires mess up everything?

Obviously he messed something up. What color wires did he connect to what?

Is the area on the same circuit as the garage? If so, it is likely protected by a GFCI. You could have tripped that and it would cut power to everything after it. That would explain why part of a circuit had no power.

It's a garage. Looked for a tripped GFCI. Everything in the garage should be on a GFCI.

Everything in the garage should be on a GFCI.
Not true.
While it's not uncommon for things to be on GFCI (and I'd check that), only thing that needs to be GFCI is 120 15/20A receptacles. The lighting may not be.

Thank you Bill, I think that is my problem, because some outlets and some lights work, but some don't. Now I just have to figure out how to reset it. It doesn't have a button like the bathroom GFCI does.
Thank you Everyone!

You will need to find the main panel or sub panel, if there is one, if there's a gfci BREAKER, it will look a bit like an oversized regular breaker, it may not look tripped, but you may have to turn it off and on again to reset it.

Three wires can mess things up easily, as you've discovered. It is also still possible that it's miswired, it may be that other devices are connected "downstream" - if you don't find a tripped breaker, you might want to try an experiment and turn the fan light on and check for voltage in the missing outlets/lights, if it's back on, you have wired them through the switch, or something like that.

Otherwise get the electrician back, you want this resolved before the drywall goes in.

I guess another possibility is that a wire may have been cut when you put the fan hanger in (I hate those things and doubt they are a substitute for a good piece of wood instead)

If it is a GFI, you need the electrician back out. You shouldn't run the lighting circuit off of a GFI. It should be a separate circuit. So, if you've got lights and outlets both not working, your circuitry isn't run correctly. "Bonus rooms" over garages very often are not designed for live loads, only storage. So often in addition to beefing up the joists and insulation, and taking care of fire exit codes fo a bedroom, you may need to run a couple of new branch circuits to the space. Your code inspector will help you to determine what is required for your jurisdiction.

"You shouldn't run the lighting circuit off of a GFI. It should be a separate circuit. So, if you've got lights and outlets both not working, your circuitry isn't run correctly."

Just so you know, this is a suggestion, not a code requirement. Just because there is lighting and receptacles on a circuit does NOT automatically mean it is incorrect.

I will say though, a garage is one of the places I never mix lighting and receptacles.