If you've already tried chemical drain cleaners and natural solutions without success, it's likely that the blockage is more severe or further down the plumbing system. Here are some practical steps you can take:
1. **Plunger**: Start with a plunger. Make sure to cover the overflow drain (if applicable) and create a good seal. Plunge vigorously for several minutes.
2. **Plumbing Snake**: If plunging doesn’t work, a plumbing snake can help reach deeper clogs. You can rent one from a hardware store if you don’t have one.
3. **Remove the Trap**: For the kitchen sink, you can remove the P-trap (the curved section of pipe) under the sink. Be sure to have a bucket ready to catch any water. Clean out any debris you find.
4. **Professional Help**: If these methods fail, it may be time to call a licensed plumber. They can use specialized tools like a hydro-jetter or camera inspection to diagnose and resolve the issue. Plumbing costs typically range from $100 to $250 for a service call, depending on your location.
Your next step should be to get 2–3 local quotes on Handyman.com to find a qualified plumber who can help resolve the issue efficiently.
— Assisted answer