You must Make Up for those Prayers You left as soon as possible
Question :
I travelled outside the Kingdom to a country which does not follow the Islamic religion and I was strict in observing the prayers, but the timing is different from the timing in the Kingdom and so I missed many of the times because I did not know the direction of the Qiblah and the time (of prayer). Should I repeat the prayers for the times which I missed?
Answer:
Yes, you should make up for those prayers you left for this reason as quickly as possible. This is because it is not considered a valid excuse for leaving them, since it was possible for you to ascertain the approximate direction of the Qiblah or to use a device for determining the Qiblah. Likewise, you could have ascertained the time, using the calendar and you could have used your watch to know one time from another, or night from day and so on. Since you did not do so, then you must make up for those prayers immediately, in sequence, even if it takes an hour or two. And Allah knows best.
Source:
Ibn Jibreen
Fatawa Islamiyah, Vol. 2 Page 430