Help WINDOWS 10, RAM, AND MINECRAFT

So I was playing Minecraft with mods. I decided my game was acting slow, so I went to add more dedicated ram. I slipped up when I was typing and typed 15 instead of 4 ( I have 16 gbs of ram installed). So I continued playing everything was normal. Then I restarted my computer for unrelated reasons. When I pressed the power button on my desktop it started up like normal, but now it shows this… A blue windows logo with a black screen behind. No spinning or anything. I restarted a few times it said preparing automatic repair and has not changed ever since. That happened 2 weeks ago.