If your tablet is currently on an older version like Android 4.1.2 or 4.2.2 Jelly Bean, you can attempt an official update:
: Connect your tablet to a computer and use official software like Samsung Smart Switch or Samsung Kies to check for and install available firmware. Manual Firmware Download & Installation goggle samsung gt-p5210 android 4.4.2 download
For a clean install or if the over-the-air (OTA) update fails, you can manually flash the stock ROM: If your tablet is currently on an older