ANSWER:

Your prayer is valid. Witr is not a mandatory prayer, it is a highly recommended sunnah, you will be rewarded a great deal if you pray it, however you are not sinful for not praying it.
Kindly refer to the following link(s):

 

Sheikh I working nightshift in my company…morning Dhuhr,Asr,magrib I will pray in room. Isa I will pray in company then I used to pray witr after 4 clck.. last 2 days I missed witr. But I prayed isa in a correct time..did my prayer is invalid.. sheikh..

Prayer | February 1, 2018 6:03 am
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I once had to travel after thuhr but just before asr started, the problem is I arrived after maghrib and had not prayed asr yet. If this happens again, and I cannot pray asr here after it begins, could I combine thuhr+asr 4 rakat each here at home before I leave, if I will arrive after maghrib?
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Can we make Dua in our own Language other then arabic as well after reciting 3xSubhana Rabial aala in Farz Salat.