The highest level of knowledge I have of computers is how to install mods for games. That being said, I have no idea what is happening to my Minecraft worlds. At first, it was just once every 5 times I went to play, but now, every time I open a world to play it looks like everything is corrupted. It's laggy and unplayable. I tried to find images similar to the problem I'm having but I haven't found any so far.
It does this whether it's a modded or unmodded world. It even happens in different versions.
If you have any idea what is going on and could help me at all, it would be greatly appreciated. Also, hopefully, you can be patient with my lack of computer knowledge and take me through it step by step.