How can I fix a loose truss rod on my guitar?

To fix a loose truss rod on your guitar, you will need to adjust it using an appropriate tool, such as an Allen wrench. Insert the tool into the truss rod adjustment hole and turn it clockwise to tighten the rod or counterclockwise to loosen it. Be sure to make small adjustments and check the neck's curvature as you go to avoid over-tightening. If you are unsure or uncomfortable doing this yourself, it's best to seek help from a professional guitar technician.