I can't (for lack of a better word) "Visualize" anything in my stories

This has been a problem for me since I first started writing. I cannot come up with what the people or places in my stories look like. I don't have much of a problem with world building, or coming up with different character personalities, but that's about it. Is there any way I can overcome this?

You could ask an artist to interpret a general idea https://tvtropes.org/pmwiki/posts.php?discussion=13252547870A59400100&page=1#25

Or just look at art in general www.deviantart.com

The nice thing about characters is, you have the option to be rather vague on what they look like. You can let the audience fill in the blanks for you on their appearance, and while it's good to give a few contextualizing clues (sex, age, maybe height and weight), you can let your audience just imagine what they look like.

One thing you can do is sort of think of it like a stage play. Come up with a few focal details of the area that are important to the scene, or really set the mood of what a place is like. What "props" are most necessary to make the scene fit? If it's set in an elaborate bedroom in a mansion, describe the fancy bed. If it's a busy kitchen, describe the area around a messy sink. If it's a fantasy forest, maybe focus on one gnarled tree that almost seems alive. Your audience can fill in the rest of the scene for themselves in their heads, basing it around those one or two setpieces you give them.

Plus, it saves you the trouble of imagining the area in extensive detail. :P

I have the exact same problem with my stories, and that's why I can't progress through them even though I already have a world going on.

One is set in High Fantasy (to be made into a CRPG), one in a middle school (my main story so far).

Another problem of mine is on how to foreshadow betrayal (though not doing so may add to the shock factor, but it reeks of Ass Pull if anything). I'm looking at Suikoden II for ideas, but I'm not sure how the bad guys would try to contact a hero ally except that the one they're trying to get in contact with is actually the Action Girl (who wields a Katana, but has affinity to the Wind element unlike Shana's Fire) daughter of one of the bad guys.

OP: Have you thought about what extent you actually need to do this?

Well, its kind of necessary for me because I kind of want to get back to writing comics; and the last time I tried writing one, the artist had to know what each character looked like. So I figured to just get the hang of it before sending the new story to the artist.

Well, if it's comics, that's a different matter. I assumed we were talking a non-visual art form.

You don't even need to know with comics. It's part of the artist's job to, y'know, work out what things look like.

My advice is try to think of vague descriptions based on their personality. If they are ditzy, give a vague description of how their face looks ditzy. It's not perfect, but it wil give your artist something to work off of, without having to go the entire nine yards of description.