If you're stuck on a quest, mini-game or another piece of in game content try reading the walkthrough on official community-maintained wikis to make sure it's not part of the challenge of the game!
If the issue you're having isn't mentioned or described there, then it's possible that you've discovered a bug that we need to know about!
How to report a bug
Find out the difference between a Bug and a Technical Issue and how to submit a bug report for each version of RuneScape.