Most of my quick quits have already been suggested - rail fence, D9P, snowball w 9 patch. Another really quick quilt is a square in a square. Alternate dark with light in center with light with dark in center. These can be strip pieced - either like a 9 patch, or with a larger square in the center (center twice the width of the outside).
Also, a bargelo can be done quickly. Draw a lightning bolt on a piece of graph paper. Decide on the size each square represents. Label the width of the strips you'll need on the line of the lightening bolt. I use 1/2, 1, 2, to represent the multiples of the strip height. Choose a number of colors, arrange from light to dark. If you want to see how it will look, draw rows of colors on another piece of graph paper. Cut the strips of paper and tape to graph paper lightning bolt, offsetting one block for each strip. Sew strips of fabric together. Cut widths as you've determined, being sure to add 1/2" for seam allowance. sew together, and you're done.
I also recommend getting back the top/quilt from the longarmer. There should be some salvageable parts. Depending on how much of it you can use, you can make it into a smaller quilt or pillows. Even the damaged parts might be able to be used, as a pet quilt if you're not comfortable using it for humans.
I agree the bleach accident should never have happened, but things do happen. I've had a problem with bleach, too, but apparently much smaller. My applique quilt top got mildewed on one corner from our boat sinking. I bleached that corner and it took out all the color of the background material. I ended up adding small appliqued blocks on each corner, large enough to cover the damage.