The answer to a supply line not working is that there are several common causes, including a clogged or damaged line, a faulty shut-off valve, or a problem with the water pressure. Some common symptoms include low water flow, dripping, or the supply line not providing any water at all. Solutions can range from simple DIY fixes like cleaning the line or replacing a shut-off valve, to more complex issues that may require a professional plumber to diagnose and repair.
If the supply line issue is limited to a single fixture, such as a sink or toilet, it may be possible to address it yourself with some basic plumbing knowledge and tools. However, if the problem seems to be with the main water supply line, or if you're not confident in your ability to safely and effectively repair the issue, it's best to call in a licensed and experienced plumber to ensure the problem is properly resolved.