Q: Pages refuses to open

This is sort of like calling your mechanic and saying, "My car won't start".

Which model iPad?

What version of iOS are you running?

What version of Pages?

Has it worked before?

If it has, what happened immediately before the problem.

In the meantime, double-click on the home key, scroll to the last time Pages was open, side to the top to remove it from recently used apps.

Next do a Forced Restart: Hold down the home and sleep buttons, wait for the Apple logo, let go of the buttons.