We are both up in years and not as small as we used to be so a problem like this can be daunting. This is under my bathroom sink I'm ashamed to confess. It was artfully hidden by baskets of supplies until the water had reached the front. The water caused the paint to flake. I removed everything and just sat an ice cream bucket under the drain until I had time and the ability to look at the problem.
First I had to find the leak. None of the joints were the problem but I found this funky piece...have no idea what it's called but it was the problem. When this piece was not in place, it leaked. If I removed it there was a big hole in the drain pipe.
Notice the piece sticking out on the left of the drain contraption. I thought on that a while. Then I remembered GORILLA GLUE!
This type of glue expands when it dries. Not good for some wood projects but maybe, just maybe, it was the solution.
Forgive my poor photography skills. I was having trouble fitting under the sink, using a flash light, gluing and taking pictures. My brilliant idea was if the glue expands why not try it on the part where the leak is...I'm creative when it comes to an out of the box solution! Glue applied. Thingy stuck back in hole. Problem solved!!! No leak. Hot dog, I'm on a roll.
Cleaned, sanded, painted and done, done and done. Donations for a real plumber can be sent to...