Hey there eeevvveee,
Thanks for reaching out to the Apple Support Communities. To get started, in the login screen pop-up that appears, are you able to see any text fields? If you are able to see a text field, tapping on the text field does not bring up the onscreen keyboard, is that correct?
If so, have you tried restarting your iPad since the issue started? If you haven't give that a try with the steps shown here: Restart your iPad - Apple Support
How to restart an iPad without a Home button
1. Press and hold either volume button and the top button until the power off slider appears.
2. Drag the slider, then wait 30 seconds for your device to turn off. If your device is frozen or unresponsive, force restart your device.
3. To turn your device back on, press and hold the top button until you see the Apple logo.
While restarting may seem like a simple step, it can often help with resolving some unexpected issues like this.
If still having issues after going through the steps above, let us know which app you're having issues signing in with, and we'll continue from there.
Take care!