Since the handheld bluetooth scanner is recognized by the tablet as a keyboard, the on-screen keyboard can get disabled. Follow the steps below to get the on-screen keyboard back.
Step 1. Go to 'Languages and Input'
Go to the settings of your tablet and go to the setting 'System'. Now select 'Languages and Input'
Step 2. Turn on your on-screen keyboard
Select the option 'Physical keyboard'. After clicking on 'Physical keyboard' you will see the option 'Show virtual keyboard'. Slide the toggle to the right to enable your on-screen keyboard while your handheld bluetooth scanner is connected.