One of two things has happened. either it has turned inside out, in which case the fabric shoud be consistant stst on one side and rev.stst on the other with no sudden change. If this is the case simple push the knitting through the middle of the DPNS to change it to rightside out.
The other possibility is that when you picked up again you accidently started knitting the wrong way. You had picked up the knitting the worng way around and where knitting back the way you had come, turning your work and flipping the stockinette. This would produce a fabric that shoed stockinette for most of it with a sudden change to reverese stockinette. Unfortunatly the only way to fix that is to tink or frog back until the change , turn your work so you are going the right way again and re-knit.