In this video

Take a thin, pointed tool (such as an awl or a specialized carpet repair needle) and carefully push the entire length of the exposed loose carpet loop back down into the carpet pile. Work to blend it seamlessly with the surrounding loops, aiming to restore the carpet's original pattern and texture. Once the loop is mostly reinserted, apply a very small amount of clear carpet adhesive or fabric glue directly onto the base of the reinserted loop. Immediately after applying the adhesive, use the pointed tool to gently press the glued loop further into the carpet pile. This helps to spread the adhesive slightly and firmly secure the fibers, preventing the loop from pulling out again. The video demonstrates this process twice to reinforce the technique.