You can pick up the sts either
1) one column at a time
2) or one row at a time. I find this easier in this situation. Put the sts to be worked on the L needle. Use the 1st (lowest) strand of dropped yarn in back to knit. Repeat.
If you worked across these sts with the working yarn, you'll need to take that row out too to get the sts down to where the dropped sts started.