I'm very new to Inkscape so please bear with me.
I'm attempting to create lineart by tracing an image using bezier curves. It was going great until I messed around trying to adjust the line thickness. So now when ever I draw a bezier curve the entire space perpendicular to the nodes gets filled in. For instance...When I attempt to draw a curve the end result instead looks like half a circle. I clicked on the button to reset parameters to default but that didn't change anything. Could I get some help please? Thanks.

Welcome to InkscapeForum!

It sounds like you might have applied a Fill to your path. You can either look in the bottom left corner of the Inkscape windows, where it shows the fill, stroke, etc. info for the selected item, or in the Fill and Stroke dialog > Fill tab. If they indicate that it has a fill, you just need to remove the fill. If you look and find that the path does NOT have a fill, then I have misunderstood.

The fill is automatically applied to any new path that you draw, because (I'm guessing) of your setting in Inkscape Preferences. It can either be set to draw a new thing (path, shape, etc.) in the same style you applied to the last time you used the tool; or to use that tool's own style every time. So for example if you want the Pen (bezier) tool to draw a black stroke every time, you can go to Inkscape Preferences > Tools > Pen, and tick This tool's own style. Then on the canvas, set up the black stroked path, however wide you want it, and no fill. Then while it's still selected, go back to Inkscape Prefs and click the bar that says Take from selection. You can do that for all the tools

Let us know if that solves the problem