This guide will assist you in removing the microphone from your Sony Ericsson T68i.
Remove the battery from the back.
Pry off the plastic cover from the top with a thin plastic shim, then remove it from the two bottom clips.
Unscrew all four Torx T6 screws.
After removing the screws, the two halves will separate. If not, then pry them gently apart.
Next remove the circuit board and screen from the device.
Use your T6 to remove the 4 screws holding the cover on.
The board and screen should just pop out at this point.
The microphone at the bottom of the rear housing can be levered out using a small screwdriver or any similar tool.