Explanation:
I think that you might have used it a lot or its just a glitch and will come back after some time.
It might be that your screen cracked.
But try re-booting if that does not work, wait and take off the battery.
Right click the cell, click add cells & it should say the options (new row above etc.)
B
Explanation:
The Alter command is used when we want to modify a database or object contain in database.
