Greetings shekar2481,
It looks like you joined the Apple Support Communities from the following page: Sign in with your Apple ID - Apple Support. This is an excellent resource if you're running into issues with signing in with your Apple ID. However, it does not sound like this is the issue. More-so it sounds like you're running into an issue with the App Store and iTunes Store completing its connection to the Apple server. Apple does offer guidance for this issue; which you can find here: If you can't connect to the App Store, iTunes Store, or other Apple services - Apple Support.
The Apple - Support - System Status page does not show that there are any current outages. So, you will want to check to make sure your iPad is able to connect to the internet.
Make sure that your device is connected to the internet
Use any web browser to connect to any website. If nothing loads, use another device on the same network to see if it can connect to any website. If no other devices can access the internet, turn off your Wi-Fi router, then turn it on again to reset it. If you still can’t connect to your Wi-Fi network, contact your internet provider for more help. If only your first device can’t connect to the internet, get help with Wi-Fi on your iPhone or iPad, Apple Watch, Apple TV, or Mac.
If you use cellular service to connect to the internet on your iPhone or iPad, make sure that you have cellular data turned on for the app that you're using. To do this, open the Settings app, tap Cellular, then turn on Cellular Data.
If the issue remains, you'll want to verify that the software on your device is up-to-date. The update process can frequently address unexpected software behavior. Here's a guide to help: Update your iPhone or iPad - Apple Support.
If you have completed all four steps on that page and still have an issue, you'll want to reach out to Apple Support directly for further assistance. You can reach out to them by clicking here: Get Support - Apple or over the phone by calling the number that is most local to your region: Contact Apple for support and service - Apple Support.
We hope this information helps you out.
Kind regards!