Thank you for your question.
A true Muslim is satisfied with himself and his place in the universe due to the knowledge that he is not merely a worthless particle within an accidental existence or an insignificant creature with no purpose or role to play in life.
He knows that lie is a chosen servant of God, holding a position of honor, trust, favor and responsibility.
He is certain of his Lord's perfection, all-encompassing knowledge and absolute wisdom, justice and mercy.
He knows that nothing is created without purpose and that God's favors and blessings are infinite and beyond human perception.
Islam emphasizes the value of human life. It also teaches that one should not despair of God's mercy and recognize that this decree is always beneficial in some way, even when it might seem otherwise.
The endurance of pain, discomfort or hardship while accepting God's decree is something that benefits a Muslim in the Hereafter and increases his reward.
Prophet Muhammad (peace be upon him) said, "No tiredness, exhaustion, worry, grief, distress or harm befalls a believer in this world, not even a thorn that pricks him, but that God expiates some of his sins thereby." (Al-Bukhari and Muslim)
Suicide indicates impatience and a lack of trust in God. It is thus prohibited for Muslims and considered among the major sins that is subject to the will of God on the Day of Resurrection; He may either forgive it or punish for it.
The so-called mercy killings come under the same ruling. Although painkillers may be prescribed for those who are terminally ill or badly injured, it is not allowed to use or be given medications that are known to cause death either sooner or later.
A basic principle of Islamic Shari`ah is that harm cannot be removed by something else that is equally harmful, so it is not permitted to use medications that will cause greater harm than the disease itself, which is the taking of a human life without a legally just cause.
As for abortion, it is unlawful in Islam to terminate a pregnancy at any stage unless there is a justifiable reason, and then, only within very precise limits.
If the pregnancy is within the first forty days and aborting it serves a legitimate purpose or will prevent harm, then it is permissible to do so.
But fear of difficulty in raising children or maintaining and educating them or the couple's belief that they already have enough children is not a permissible justification for abortion.
After four months, it is not lawful to abort a pregnancy unless a group of trustworthy specialists decide that keeping the fetus in its mother's womb will lead to serious medical consequences or threaten her life.
Even then, it may only be done after all means of eliminating the danger and keeping the fetus alive have been exhausted. In this case, the concession allowing abortion is made in order to avert the greater of two evils or serve the greater of two interests.
We hope this answers your questions.
Keep in touch.
Source: This answer is based on the book of Clear Your Doubts about Islam by Sahih International.