@ Madiha Alvi
Tests will be held as per schedule announced by NTS. So, take the tests whether schools are closed or not as tests will be held.
Secondly, Phase-II is for those who have not applied before. You can not apply for the same post for Phase-II if you have applied before.
Thirdly, you will receive roll # slips sooner or later as these have been dispatched. If you don't receive at the last moment, don't' worry. Just get print of your Roll# Slip from NTS site and go to the exam center with CNIC. You will be allowed to take the test.

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