General aviation pilot approaching downwind reported while attempting to change the landing gear indication bulb they became distracted and temporarily lost control of the aircraft.

Narrative

Distraction During Landing Caused DisorientationZZZ tower had instructed me to enter left downwind for XXR and report midfield. As I was lining up and entering the extended left downwind for XXR; I attempted to lower the landing gear but did not get a green light (the aircraft has a single green light to indicate that the gear is down and locked). After a second attempt; I thought I could replace the bulb in a few seconds using the bulb from the low vacuum caution light next to it.While holding a flashlight in my right hand; I unscrewed the vacuum caution light with my left hand. After unscrewing the vacuum caution light from the panel; it slipped from my hand and fell to the floor while I was holding it in my palm and attempting to unscrew the landing gear bulb at the same time. I looked down to search for it on the floor for a few seconds but was unable to see it.When I looked up; I had lost visual contact with the runway and was momentarily disoriented because the lights on the ground did not look as I expected. After checking the instruments; I realized that I had turned almost 90 degrees to the left; crossed over the departure end of the runway; and the runway was now behind me. I had also lost a couple of hundred feet of altitude.At this point; the tower called and inquired if I was okay; noting that I had flown over the departure end of the runway. The tower gave me bearings; altitude information; and issued new clearance for a right downwind for XXR; clearing me to land.During the landing flare; I noticed that my landing light had also become inoperative. An airport operations truck provided light by following the aircraft and using its headlights to assist with my taxi to the tie-down area.