People are unnecessarily alarmed. You can practise ordinary Pranayama exercises without the help of a Guru. A Guru is necessary if you want to practise Kumbhaka or retention of breath for long time and unite Apana with Prana. The books written by realised Yogins can guide you if you are not able to get a Guru. But it is better to have a Guru by your side or you can get the lessons from him and practise them at home. You can keep regular correspondence with him. You can retain the breath from to 1 or 2 minutes without any difficulty or danger. If you cannot get a realised Yogi, you can approach senior students of Yoga. They also can help you.