Aside from the following,
1. Broaden your horizon
2. Have a program of life
3. Make a difference
What one can do to regain the life purpose?
Then think of another purpose of your life, because you cant nothing to do if it lost, just find another purpose of life so that you can enjoy your life. Dont think too much so that it cant stress you, because the more you think of it the more you lost your purpose of life.