After confessing to a wee-knitting problem here last week I decided that the only way was to insert a lifeline - and here is how I did it.
1. You need to firstly mark the row where you want to get back to, and then chose a row or two above that just in case your lifeline isn't quite right.
2. Pick up the stitches very carefully, it helps if the yarn like this one has very defined stitches. I picked up the stitches with the wrong end of the needle that I use to weave ends in. You can't use the pointed end as you will not be able to pick up the strand of yarn evenly. A bit obvious, but it is best to use a colour for your lifeline that is in a contrasting colour to your work.
3. Work your way carefully across the row. Taking care to pick up the correct stitch, ie. knit OR purl stitch in my case for stocking stitch...and making sure not to cross-over into the row above or below.
4. This is the scary part. Start ripping out your work above the lifeline and stop a row or two above. If you are confident your lifeline is OK rip away, but if not you can pick up your stitches with your needles at this point. I find it good to have a crochet hook handy here, just in case there are any stitches that pop of the needles, or you have missed with your lifeline.
I went for broke and ripped right away to the lifeline.
5. Insert your knitting needle back through, if you haven't decided to pick up stitches that is, and pull out the lifeline....and voila we are back on track.