I tried the vinegar and salt weedkiller. And it didn't work- help!

http://www.goodhousekeeping.com/home/gardening/advice/g777/homemade-weed-killers/

Some people swear by boiling water. This link gives you more tips.

Oh no! Did you also dig them up??

Boiling the water will do the trick!

My guess is your solution wasn't strong enough or you did not drench the weed. The link Sandra provided is perfect! Every day I boil 2 kettles of water. Then I walk around and douse the offending weeds then let the sun do its magic. Later I walk around and look for the brown spots, dig up the dead weed roots and all and dispose. Granted not everyone has the time to do every day, but even once a week makes a difference!

It didn't work well for me, either. I have found, however, that plain old BOILING water poured directly on the weed will kill it. If you have alot of weeds it is a time consuming process but Hey, I got my exercise walking back and forth from the kitchen to the yard.

wont it kill grass around the weed also?

I too use the "boiling water" method. Works for me.

Depends on the weed...salt/vinegar/soap is a fair defoliant for tender plants, not so much for those that have a thick root (dandelion), or are ,woody, like poison ivy. And even then must be applied more than once! Elbow grease is the best and it's free!