If you mean, where Islam is not practised in toto, in letter and spirit, then most of the Islamic countries are not following Islam.
Japan used it in WWII but doesn't anymore. Predominantly, Islamic countries of Burma, Saudi Arabia, Iran, Sudan and Syria have had recent crucifixions.
in which parts of the world are there no islamic countries?
No predominantly Muslim countries have legalized same-sex marriage.
It is unclear what is meant by "International neighbors". If the question is asking which former USSR states are predominantly Muslim, those would be: Azerbaijan, Kazakhstan, Uzbekistan, Turkmenistan, Kyrgyzstan, and Tajikistan. If the question is asking which non-Soviet states bordered the former USSR that were predominantly Muslim, those would be: Turkey, Iran, and Afghanistan.
By forming Islamic armies, conquering non-Islamic countries, and making them into Islamic countries. Simple.
in which parts of the world are there no islamic countries?
In modern times predominantly yes, but there are others. Not in ancient Egypt though
Since Egypt is located in the western hemisphere they are a predominantly Islamic country.
The piano is a universal instrument and is popular in all countries.
The most populated Islamic countries in Asia are Indonesia, Pakistan, and Bangladesh.
The Muslim religion is predominantly throughout the Middle East, the largest population if the Islamic Faith is Indonesia.
I am not sure about the exact count, but many Islamic countries use the Arabic language.