Understand that you're not a mental professional and the last thing you'd like to see is your parent commiting suicide.
1. When the situation becomes so drastic and overwhelming. Call emergency center immediately.
2. Assess lethal intent.... Understanding the seriousness of your parent's desperation.
3. Ask if he/she is truely serious about hurting himself/herself. Thisis mostly ignored as a sensitive question but it's very important as to save life.
4. Ask about the plans. Ask how she/he intended to go with the plan. The means to commit suicide.
5. Ask if you can pray for the person. Prayer is very effective in introducing hope to the hopeless mind. People feel loved when prayed for. The advantages are plentiful.
6. Never go around babbling about the fact. Be discreet, in order to avoid pressuring your parentn to that intent.
7. Do not hesitate either. From your observation, if you realize that your parent is likely serious about the issue, contact family members calmly, to figure out some solutions.
8. Get help from other families and friends. Do not wait. The more you wait, the more the intention grows. Never cover-up family problem when it becomes suicidal.
9. Let your parent know how important he/she is in your life. Give examples, including the tragedy they might cause by hurting themselves.
10. Additionally, let them know your capablities and how they can be proud of you in time to come.
Keep reminding yourself about the source of every decision. You can't blame yourself. Relax and do all you can. Worry might only take away the creativity you need to deal with such delicate situation. Love your parent and continue to be a good child.