Seriously?

Walk around looking for people for a day or two. Notice the animals are gone and maybe notice the absence of insects.

Start living out of the local grocery store because I don’t have enough food at my current place. I’d probably get myself a gun from a Walmart or something because if I encounter someone else, they might be hostile without laws or society

Probably start crying myself to sleep when I realise I’ll never see another human and never fall in love.

I’ll probably watch as the utilities and services slowly fail over the course of several weeks. The electrical plants will run out of fuel within a day or two, but the heat of the furnaces and the angular momentum of the turbines will provide a few days of power while they wind down. Nuclear plants, hydroelectric, solar, and wind will be stable for longer but they’ll all fail within weeks or months without upkeep, unless I’m really really lucky.

Sewage and water will probably be gone in a week, since there’s a fair amount of maintenance and upkeep with water purification and/or treatment plants. Lots of switching tanks and balancing chemical levels.

Clinically major depression will set in after a few days to a week or two due to total isolation. I’ll have trouble sleeping because no natural sounds will exist at night except for the weather. I may start to go insane when I start becoming depressed, thought the insanity may hold off for as long as several years if I’m very lucky and actively try to maintain my mental health. I start talking to videos as though they were conversations, just to talk to something, until the power plants supplying the servers go dark.

Eventually, I will accept that I am absolutely alone. My friends and family are gone forever. My career is over before it began. Both pillars of my existence, family and contributing to human knowledge, are now meaningless.

I will also realize that life will be harder than anything possible to imagine. For the remainder of my life, I will be limited to the abilities of a single individual and the resources of whatever stocks the shelves of stores within a several dozen mile radius. The roads will probably be full of wrecked cars, crashed when people vanished, and all human infrastructure will degrade rapidly.

After these realizations, in the face of inevitable death, lifelong absolute solitude, and perpetual unrelenting hardship I will probably drive to the nearest military installation. By then, I know that my life is meaningless. However, I still fear pain. I would probably construct a helmet of high-velocity explosives and end my life.

The universe looks on with indifference at a single smear of human among the smouldering wreckage of humanity. It had never been a significant planet anyway, in the cosmic sense anyway. Now, even less so.