Ok, so lemme start of with a bit of background. I had to tend to the food for today, and I left my computer on, wanting to continue playing Skyrim after finishing my task. However, when I got back, the Skyrim window was completely messed up, having the normal window border and filling up 4/5 of the screen. After shutting Skyrim down, Steam had to synchronize, for some reason, which it always does when I shut down a game for whatever reason. Usually, turning my computer off and on again let's me play. But, for one reason or the other, my computer refuses to start up. It goes like this; I turn on my computer, the Lenovo logo appears and just as two circles of the spinning circle thingy pop up, they just stop, and the computer does not boot up. What is wrong here?

Additional info: Don't know the exact specs of my pc, although I know I bought it as a "Medium Gamer Lenovo Stationary PC" or something like that.

This has not happened before, and I upgraded to Windows 10 a while ago.

My computer cannot identify the problem with a boot-up scan, and I am not risking resetting my pc.

Please answer my question as quickly as possible! Thanks in advance.