One day last week I reached into my knitting bag to find that all the stitches on one needle had fallen off. I was having problems picking up the stitches so I decided to pull out a few rows. Sometimes it's easier to pick up stitches this way.
I hadn't picked up the stitches by the next morning and wanted to take my knitting with me. So I broke the yarn and started the second sock. The nice thing about this is that the two socks will share more colors this way.