If you have a WiFi connection but can't access the internet try the following:
Not quite sure where it is located in your Tab but go to Menu > Settings > Apps > swipe right side to ALL Apps, then scroll down and find Download Manager. The Apps are listed alphabetically, with working apps first then disabled apps.
Tap to enter Download Manager. If there is an Enable button tap it then try to go online.
If it says 'disable' tap to disable, then clear cache. reboot Tab then navigate back to download manager and enable it as above.
See if you can access You tube or the internet with your browser.
if your internet now works, try this link to which shows how to install Play Store on your device.
Hopefully this is of some help.