My iphone was stuck in headphone mode due to what I thought was a hardware issue.
The repair went well. I used the ifixit guide and was very easy to follow. My tools performed well except for me #00 screw driver. Not sure if I just got a bad one or what but it was too flat instead of being sharp enough to actually get to the screws.
Just take your time, this repair is pretty difficult due to how far you have to strip the phone down.
iPhone 4S Headphone Jack & Volume Control Cable
Phillips #00 Screwdriver
P2 Pentalobe Screwdriver iPhone