How to do 2d in modern opengl

Im about to give up on this, so if anyone in here could please help me I would appreciate it

all I want is to be able to draw textured quads against an orthogonal projection where screen space is not from -1, 1 but from 0 to screen width and from 0 to screen height so I can map vertices directly to pixels


You said everything in your post. So by reading some docs about OpenGL you should easily find that:

glViewport (0,0,100,100);
glMatrixMode (GL_PROJECTION);
glOrtho (0,100, 0,100, -1,1);
glMatrixMode (GL_MODELVIEW);

or so, will be great.

Oh Im sorry I meant how to do this in modern opengl

Build the same ortho matrix by hand and send it to your shader. The man page for glOrtho describes how the matrix is built, so that should give you the info you need to know to build it manually.