I have an incoherent and chaotic UV map my UV map is completely incoherent, pieces are spread all over the map without bigger sense, on the left is my model when all I wanted to color were eyebrows and nose

I first modeled my model, then I tried to add textures, but then I realized she has no eyebrows, co I join them, I wanted also modify a bit her nose to be easier to color

When I return to textures, eyebrows were added ON the map, causing this weird coloring

I would like to know if there's a way to re-create the map so the pieces won't lay on one another
I didn't apply the mirror and sub-surface modifiers and my model has every part (like eyes, scarf, T-shirt etc.) in an another "layer" (that thing on the top right). I'm writing this if it can help.

I'm a lil concerned, it's my first 3D model and I don't want to re-model the whole thing :/
Ok.
First step: delete the map (make a backup copy of the .blend file first).

Then you should try the several unwrapping options. If you don't find one that make a good map, you could try unwrapping the mesh in more steps (some faces per time). For example you could map the two symmetric halves separately.