Everything You Need to Understand Fabric Grain and Grainlines

Unpin the fabric.
Dampen the fabric to relax the fibers.
Work the bias of the fabric by holding opposite ends of the bias grainline. Use your pulling ability to twist the fibers into a perpendicular position.
Repeat the pinning process and test the fold to see if you have achieved moving the fibers to straighten the fabric grainlines.
A pattern can not be straightened that is printed on fabric that is off grain. Stripes, plaids and patterns that are printed askew will never lineup on a finished product. Don't waste your time trying to "make it work", use the fabric to test patterns or wash windows. Until you can recognize grainlines in fabric, if you want striped or plaid fabric, buy fabric that has the pattern woven rather than printed on the fabric.