بسم الله الرحمن الرحيم
Think in your heart about Qiblah i.e. consider the signs and other indications to determine the direction of the Qiblah; if there is someone who knows the direction then ask him, then after thinking in heart whichever direction the heart tells to face turn to that direction. If you are boarding any vehicle then get down and offer salah on some suitable place. If you are in train, bus etc and it is not in your hand to stop it then you may offer salah on that vehicle. If you are able to offer salah with qiyam, ruku, sajdah then offer salah with qiyam, ruku, sajdah and there is no need to repeat it later. Otherwise, offer salah at that time as you can and later on re-perform it.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.