Should I just call an electrician?
The circuit goes from outlet to outlet to switch to outlet etc. in a somewhat logical manner. The wires can come loose at any point on that circuit including in an outlet that still has power.
SOMETIMES the power runs thru the ceiling light boxes as well.
You can save the electrician time by putting a post it on every switch and receptical that is out.
If ther are only a few outlet affected you can pull them out and check the connections. 75% of the time it will be a bad connection on the back of a receptical.
There is also the likelyhood of a junction in the attic/basement or buried behind a wall by a hack remodel job.
Best case, I would find it and be done in a 1/2 hour. Worst case it could take 1/2 a day.