Almost exactly a year ago, I found a subreddit called r/TimeTravel. The first post was someone asking a very simple question: How can I go back to the past and change things? I thought this was a troll subreddit, to be honest. So, I wrote a troll comment, which I'll paste below. But I'm writing this post a year later because I just got a private message from someone, asking if my time travel trick really worked. This is not even close to the first message I've received in response to this comment. Someone even bought the laptop I referenced.
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Look for a used IBM Thinkpad 700. Install the earliest beta build of Windows 95 (March 1993, when it was still just codenamed Chicago). Open two instances of the date/time settings. Change one of them to 11:11 AM on April 1, 1948. Change the other to 11:11 AM on January 4, 1984. Press okay on both as quickly as possible.
Then, disconnect the laptop from the power source (although you might want to bring the charger with you, to return to other timelines). Go back into date/time settings and change the date and time to whenever you want to travel.
If you don't disconnect the laptop from the power source, it will try and transport as much of the connecting wall as it can, which usually leads to some truly fucked up shit. DO NOT FORGET TO UNPLUG YOUR THINKPAD.
Every time you reboot you have to redo the simultaneous date setting. If you're going back before electricity, for goodness sake bring a solar charger.