This is why you here so much about backups.
For now try going back to when and how it worked, try SAFE MODE and do not tinker with those settings if you recover.
At worse you have to reinstall the OS and then from your backups.
Hello, I screwed something up in my pc and I need help. I had been having issues with my RAM in a game I've been playing (not enough RAM), and I'd heard that unchecking a box in MsConfig titled "Maximum Memory," with a text box beneath it. After unticking the box, I restarted my PC, and immediately ran into a problem: the thing wouldn't start, and sat on a black screen. I restarted it again, and now it's stuck in an Automatic Repair loop. Any of the "normal" fixes to escape the Repair loop do not work, and I cannot boot my computer into safe mode. Please send help!

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