Welcome to the forum!
It's hard to say without being able to see it. Would you please share your SVG file?
I would suggest not using the Eraser tool. Even though it is part of Inkscape, and it is a vector tool....erasing is more of a raster concept and just is not capable of creating high quality vector graphics. (Well, not unless you really know what you're doing.) You will be better off with vector graphics in general, in the long run, to learn how to manipulate paths with the more traditional vector tools and techniques.
If you're using the Eraser tool multiple times, and without understanding how it works, as you've learned, you can easily get to place where the only way to fix it, is either to start all over, or undo back until you're in a better position.
Anyway, we can get a better idea what's happening if we can see the SVG file. And once we see it, we can explain the more traditional techniques for what you want to accomplish.
