When my folks were in town for Christmas, they noticed that when they plugged their phone charger into one of the guest bedroom outlets, it made the table lamp dim and flicker. I took a look at the outlet they tried to use and saw that the ground wire connection was loose. I tightened it, screwed the outlet unit and cover back into place and cut the power back on. My wife, who was up in the guest room, said the alarm clock hadn't come back on. So I went back to the circuit breaker to see if that circuit had tripped. It hadn't. I turned it off and back on anyway, but no dice. I took the alarm clock out of the wall, tried it in the other outlets in the room and none of them worked.

The circuit switch that those outlets are on also powers the outlets in an adjacent guest room. Those outlets work - so it's just the outlets in the guest room my folks were staying in. Help!

A loose ground wire is not going to affect delivery of power. I would guess there are additional loose wires at that receptacle. Best to replace the recpt as long as you have the box open.