Lock on ipad

A lock symbol on the top of your iPad is likely telling you have rotation lock turned on. This would prevent you from using the iPad only in Portrait, not landscape.

To remove the lock, swipe down from the top right hand corner of your iPad to bring up control center. If you see a padlock with a circular arrow and it is red, tap that icon to return rotation to your iPad.

This however would not have any effect on your ability to print from your iPad.

When you try to print, what if any error message do you see?

What lock? Please read Writing an effective Apple Support Communities question. We are here to help. We are all users. We are not mind-readers nor clairvoyants. We only know what you write down and tell us. Be specific and thorough. Include your hardware information and installed version of macOS.