If you are in a mission and some of your fellow operatives
are killed, continue to complete the mission. When starting a
new mission and the screen that asks if you want a default plan,
do not select "Yes". Instead, click "No"
and go on. When you reach the character selection screen, go down
to the bottom right corner and you should see the "Save Plan"
and "Load Plan" options. Click on "Load Plan"
and select the one that reads "m**", where * is a number
that corresponds to the mission (for example, m1, m2, m3, etc.).
Look at the characters in the box that contains the ones selected
for the mission. If you see one of the dead operatives in that
box, do not remove him or her -- just start the mission. After
this, you should have that operative with you alive and well.

Strategy: by Gamer003
Strategy: Equipment: by Gamer003