You could unravel the tangle by taking out the end. If the tangle looks too difficult to unravel, you can remove completion, draw on it to view where it leads to in the tangle, then pull on that portion up until completion slips out. Do this over and over and quite soon you would have unraveled the tangle. Retie your terminal knot.
Tangles happen when loops of line are trapped by various other loops. Such loops are often similar to slip knots, during that the knot vanishes when the caught lines are drawn out. The trick, therefore, is to check if a loop is a caught one, determined through parallel lines going under a solitary line, and also drawing out the trapped loop so the trapping lines can unravel totally. Pull on a loophole and also see where its extension is, after that take out the proceeding line to eliminate the trapped loophole.