I have double sinks in the bathroom and neither drains!

Draino, snake them both. Landlord.

Sounds like a tree is too close.

Sounds like there is a clog in the goose neck under the sink. Use a wrench to take it apart and see what is in there... you'd be surprised the collection of gunk that soap, shaving cream, whiskers, toothpaste etc. make. That would be my first suggestion, if it is clear... use a snake (not a real one.. lol) and go into the lines that exit through the wall.. could be a blockage. One time someone flushed a dish rag in the toilet and it caused the same problem... just sayin"

You could try baking soda and vinegar to try and flush them out. You may need someone to take the piping apart to see if there is a massive backup, that was the case in our master bath. Once the pipes were disassembled and manually unclogged, they have been fine since.

I recently had a clogged drain in the bathtub so I bought Drain Pro Gel 64 oz. I bought it at Big Lots.I closed the drain and poured about a half a cup over the drain and let it slowly work and it did. I also poured about a quarter of a cup in my toilet bowl, it sparkles. Any drain liquid will do the job so pour about a quarter cup in each sink and let it set for awhile, repeat if necessary.

Remove the P Trap and clean it out. Also the rod that lifts and lowers the plunger can trap hair and debri. If that doesn't do the job you may have a clog down the line and it will need to be rodded through the P Trap drain connection.

Baking soda and vinegar turned my tub drain into a volcano. No lava, lots of gooey hair balls

I like non-chemical Robotics Drain Cleaner, and I get the powdered. You might with some warm water, and pour down the drain before you go to bed at night, run hot water in the morning. Use a snake to see if its clogged with hair that you can get a hardware store, and clean out the trap below.

https://www.youtube.com/watch?v=8PI0iaIB6-4

I use baking soda and vinegar. Pour baking soda first then vinegar and it fizzles and drain is clear. Safe and simple. We all have these items in the pantry. Good luck.

AM GOING WITH THE SODA AND VINEGAR APPLICATION. THANKS TO ALL

Check vents for obstructions

Baking soda and vinegar ...then flush with hot water